BOXY TRUCKS
A mud-covered, lifted early Ford Bronco with cut fenders parked at a forest campsite beside a tent
FORD BRONCO · U13 / U14 / U15 · 1966–1977

Ford Bronco (1966–1977)

U13 ROADSTER · U14 HALF-CAB · U15 WAGON170 / 200 I6 · 289 / 302 V8DANA 30 → DANA 44 FRONT (1971)FORD 9-INCH REARDANA 20 TRANSFER CASE

“A 92-inch tin box with flat glass, a column shifter and a coil-sprung front axle that the Jeep didn't have. It rusts, it wanders if the caster is off, and a good one costs what a new truck does. Nobody who owns one cares.”

PART 01

Overview

Where it came from, why it matters, and how it changed year to year.

The story

In August 1965 Ford announced a truck that owed almost nothing to its pickups. The Bronco got its own box-section frame, a 92-inch wheelbase, flat glass all round and door skins that were the same left and right until the hardware went on. It came only with four-wheel drive and was aimed straight at the Jeep CJ-5 and the International Scout. Twelve model years and roughly 225,600 trucks later, it had lost the sales war. Fifty years after that, it is the Bronco collectors want most.

THE MUSTANG MAN'S OTHER IDEA

The Bronco began with Ford product manager Donald Frey, who had also conceived the Mustang. Paul Axelrad engineered it, clay models were built in mid-1963, and Lee Iacocca approved it for production in February 1964. Its targets were the CJ-5, the Scout and Toyota's Land Cruiser. The wheelbase sat between the Jeep's 83 inches and the Scout's 100. Up front, instead of the Twin I-Beam of Ford's bigger trucks, the Bronco used a solid axle on coil springs, located by radius arms and a track bar. Ford quoted a 34-foot turning circle.

Launch power was the Falcon's 170-cubic-inch six, rated at 105 hp and toughened with solid lifters, a six-quart oil pan, an oil-bath air cleaner and a carburetor float that coped with steep angles. A 289 V8 followed in March 1966. Every truck had a column-shifted three-speed and a Dana 20 two-speed transfer case. You could have a wagon, a half-cab pickup or an open roadster, and the dealer could add a snowplow, a winch, a power take-off or a posthole digger.

GROWING UP, SLOWLY

The Bronco changed in small steps. A Sport package arrived for 1967, along with a dual master cylinder. The roadster, which never sold, was dropped after 1968. The 302 replaced the 289 for 1969, and electric wipers took over from vacuum ones that year. In 1970 the Sport became its own model. Midway through 1971 the Dana 30 front axle gave way to a stronger Dana 44, and 1972 brought the plush Ranger trim and the end of the half-cab.

For 1973 Ford finally offered a C4 three-speed automatic and power steering, and the 200-cubic-inch six replaced the 170. The transfer-case lever changed from a T-handle to a J-shaped pattern. Sales peaked at 25,824 in 1974. The last big update came for 1976, with power front disc brakes, a front anti-roll bar and a new Y-type steering linkage that owners still argue about. The 1977 trucks got a heavier-duty 9-inch rear housing and fuel doors in place of exposed caps.

BAJA, AND THE RACE TRUCKS

In 1965 race-car builder Bill Stroppe put together a team of Broncos for long-distance off-road racing, partnering with Holman-Moody. The Stroppe/Holman/Moody trucks ran the Mint 400, the Baja 500 and the Mexican 1000, the race that became the Baja 1000, and in 1969 SHM entered six Broncos in the Baja 1000. The most famous Stroppe-shop Bronco of all, Parnelli Jones's Big Oly, won the Baja 1000 in 1971 and 1972.

Ford cashed in. From 1971 dealers sold a Baja Bronco package designed by Bill Stroppe, with an automatic, quick-ratio power steering, fender flares over Gates Commando tires, a roll bar, reinforced bumpers and red, white, blue and black paint. It cost $5,566 when a regular V8 Bronco was $3,665, and only 650 were sold over the next four years. Genuine ones now sell for serious money: Bring a Trailer results from 2025–26 run from $72,500 to $178,315.

HOW IT ENDED, AND WHY IT NEVER DID

By the early 1970s buyers wanted more room and more comfort, and the Chevrolet Blazer and the Scout II had both. Ford planned a bigger F-100-based Bronco for 1974, but the fuel crisis pushed it back to 1978. When the full-size Bronco arrived it was a foot longer in wheelbase and up to 1,600 pounds heavier. The little Bronco was done.

The afterlife has been something else. Hagerty says values nearly doubled between 2016 and 2019, and the restomod business took off. On Bring a Trailer, 306 complete early Broncos sold between August 2025 and October 2026. The middle half of the Coyote-swapped and shop-built restomods went for about $122,000–166,500, and the top sale reached $325,000. Ford noticed: its designers scanned the design chief's 1976 Bronco while shaping the 2021 Bronco. Hagerty did record a 12 percent drop in the second quarter of 2026, but a driver still costs $50,000 or more.

SIDEBAR · BIG OLY

The Bronco that won Baja on a borrowed tank of gas

Parnelli Jones took a mostly stock Bronco to the 1968 Baja 1000, and it went badly. With Stroppe mechanic Dick Russell he built something else: a 1969 Bronco on a chrome-moly space frame, with aluminum and fiberglass panels, a 351 Windsor, a C6 automatic, a spooled rear axle and a sprint-car wing for a roof. Olympia Brewing sponsored it, hence the name and the gold paint. It broke an axle on its 1970 debut, then won the Baja 1000 in 1971 in 14 hours 59 minutes, and again in 1972.

That second win nearly didn't happen. At the last checkpoint helpers filled the water jugs with gasoline, and the truck ran dry 15 miles from the finish. Jones traded $20 and a bottle of tequila for fuel siphoned from a Volkswagen. It lived at Vel's Parnelli Jones's race shop for decades until Mecum sold it in Indianapolis in May 2021 for $1.87 million.

A mud-covered, lifted early Ford Bronco with cut fenders parked at a forest campsite beside a tent
EARLY BRONCO · LIBERTY RECREATION SITE, WASHINGTON
A blue early Ford Bronco with a red tube bumper climbing a sandstone ledge at Moon Rocks OHV Area
EARLY BRONCO · MOON ROCKS OHV AREA, NEVADA
Two lifted early Ford Broncos, one blue and one stripped white roadster-style truck, on a gravel lot below desert mountains
EARLY BRONCOS · CLASSIC BRONCO STAMPEDE, ARIZONA
A blue early Ford Bronco with auxiliary lights beside a pickup camper at a hunters' camp on the Moose River Plains, Adirondack Forest Preserve, in the 1970s
EARLY BRONCO · MOOSE RIVER PLAINS, ADIRONDACKS

Year by year

What changed, model year by model year. Sweet spot Beware

  1. 1966Launched in August 1965 as a roadster (U13), half-cab (U14) and wagon (U15) with the 105 hp 170 six, column-shift three-speed and Dana 20. The 289 V8 arrives in March 1966. 23,776 sold
  2. 1967Sport package, dual master cylinder with split brakes, self-adjusting brakes, optional 11.5-gal auxiliary tank
  3. 1968Locking front hubs, revised bumpers and side-marker reflectors. Last year of the roadster
  4. 1969302 V8 replaces the 289; electric wipers replace vacuum ones midyear; steering stabilizer standard
  5. 1970Evaporative emissions controls and smaller fuel tanks. The Sport becomes a separate model
  6. 1971Dana 44 front axle replaces the Dana 30 midyear. Baja Bronco package introducedSweet spot
  7. 1972Ranger trim arrives; last year of the half-cab; fuel tanks reduced again
  8. 1973C4 automatic and power steering optional; 200 six replaces the 170; J-shift Dana 20 with a 2.34:1 low range from midyear
  9. 1974California-specific emissions equipment; best sales year at 25,824
  10. 1975Catalytic converter and unleaded fuel. CJ Pony Parts lists the 302 at 125 hp net
  11. 1976Power front disc brakes, larger rear drums, front anti-roll bar, quicker steering box (about four turns lock to lock) and the unloved Y-type steering linkageSweet spot
  12. 1977Heavy-duty 9-inch rear housing, fuel doors instead of exposed caps, 14.4-gal plastic main tank and 8-gal auxiliary. Last year before the full-size BroncoSweet spot
PART 02

Specs & capability

How it’s built, what it can do, and what fits under it.

How it’s built

The early Bronco is a body-on-frame 4x4 built on a box-section ladder frame of its own, shared with no other Ford. A solid front axle rides on coil springs, located by two forged radius arms and a track bar, while the Ford 9-inch rear axle sits on leaf springs. Every Bronco had four-wheel drive through a gear-driven Dana 20 transfer case, with locking hubs at the front. The factory data plate on the glovebox door records the body series, engine, transmission and axle codes.

CHASSISBox-section ladder frame92-in wheelbase, 151.5 in long; frame unique to the Bronco
FRONT SUSPENSIONCoils, radius arms, track barCaster is set by the C-bushings; Ford quoted a 34-ft turning circle
AXLESDana 30 → Dana 44 · Ford 9-inchDana 44 front from mid-1971; king pins on the Dana 30, ball joints on the Dana 44
TRANSFER CASEDana 20, gear-driven2.46:1 low with T-handle (1966–72); 2.34:1 with J-shift (1973–77)
ENGINES170 / 200 I6 · 289 / 302 V8289 from March 1966; 302 from 1969; 200 six from 1973
BRAKESDrums → power front discs (1976)Dual master cylinder from 1967; disc conversion kits for 1966–75

Variants & engines

YEARSPLATFORMENGINEOUTPUTWORTH KNOWING
1966–1968U13 roadster · U14 half-cab · U15 wagon170 I6 · 289 V8 (from March 1966)170: 105 hp · 289: 200 hpColumn-shift three-speed only. Sport package from 1967. The roadster was dropped after 1968.
1969–1972U14 half-cab · U15 wagon170 I6 · 302 V8—302 replaces the 289; electric wipers from mid-1969. Sport a separate model from 1970. Dana 44 front from mid-1971. Half-cab ends in 1972; Ranger trim arrives.
1971 on (≈ 4 years)Baja Bronco (Stroppe)302 V8, automatic—Quick-ratio power steering, flares, Gates Commando tires, roll bar, tricolor paint. $5,566 new; 650 sold.
1973–1975U15 wagon200 I6 · 302 V8302 (1975): 125 hp netC4 automatic and power steering optional from 1973; J-shift Dana 20 with 2.34:1 low.
1976–1977U15 wagon200 I6 · 302 V8—Power front disc brakes, front anti-roll bar and Y-type steering linkage. 1977: heavy-duty 9-inch housing, fuel doors, plastic tanks.

Capability numbers

Wheelbase92 in (2,337 mm)
Length151.5 in (3,848 mm)
Turning circle34 ft (10.4 m) curb to curbFord launch release, 1965
Fuel tank14.4 gal main + 8 gal auxiliary (1977)Capacities varied by year; an 11.5-gal auxiliary tank was optional from 1967
Transfer-case low range2.46:1 (1966–72) · 2.34:1 (1973–77)
Engine output170 I6: 105 hp · 289 V8: 200 hp · 302 V8 (1975): 125 hp net
Pickup box (half-cab)32.8 cu ftFord launch release

Wheels & tires

FACTORY TIRES
G78-15 and similar bias-ply sizes on 15-in steel wheels (factory)H78-15 largest factory option (1970 owner's manual, as quoted on ClassicBroncos)
Bolt pattern5x139.7 (5x5.5")
OffsetBackspacing 3.75–4.25 in for uncut fenders (Performance Plus Tire)
LIFTBIGGEST TIREWHAT IT TAKES
Stock30x9.50R15The safe choice on uncut fenders; 31x10.50R15 may lightly rub at full stuff or full lock, and 235/75R15 bolts on
2–3 in31x10.50R15 (up to 32 in)Uncut fenders, with 3.75–4.25 in of wheel backspacing
2–4 in, cut fenders33x12.50R15Rear fenders cut for flares; backspacing 3.25–3.75 in. Check caster and C-bushings after lifting
Bigger lift plus body work35x12.50R15Bigger suspension or body lift and trimming

Forum consensus, not a guarantee: wheel offset, tire brand and suspension wear all change clearance. Confirm before you buy.

Production & special editions

Ford built about 225,600 early Broncos at the Michigan Truck Plant in Wayne, Michigan, over 12 model years.

Total built≈ 225,600 (1966–1977)
Best year1974: 25,824
Worst year1975: 13,125
AssemblyMichigan Truck Plant, Wayne, Michigan
Roadster (U13)1966–1968Doorless open body, the cheapest Bronco; dropped after 1968 for lack of sales.
Half-cab pickup (U14)1966–1972Popular with fire and towing operators; dropped after 1972.
Sport1967 package; model from 1970Chrome trim, wheel covers and red-painted FORD grille lettering.
Baja Bronco1971 on (≈ 4 years)Designed by Bill Stroppe and sold through Ford dealers: automatic, quick-ratio power steering, flares, Gates Commando tires, roll bar, tricolor paint. $5,566 new; 650 sold.
Ranger1972–1977Top trim with body stripes, cloth seats, woodgrain door panels and carpet.
PART 03

Buying one

What to pay, what to check, and how to tell a good one from a clone.

What they cost

Values roughly doubled between 2016 and 2019 and kept climbing, but Hagerty recorded a 12 percent drop in the second quarter of 2026. Who built the truck now matters more than the year.

Project / needs work$9.6k–37k
Driver (stock or mildly modified)$41.5k–70k
Excellent original / Baja Bronco$70k–185k
Restomod (Coyote swap, shop build)$122k–166.5k, up to $325k

Based on 306 complete early Broncos sold on Bring a Trailer, August 2025–October 2026 (middle-half ranges). The median stock or mildly modified truck sold for about $55.5k. Baja Broncos sold for $72.5k–178.3k, and ICON BR builds for $233k–240k. Hagerty says a driver-grade truck still costs $50,000 or more. Prices move; checked October 2026. See live listings below.

What to check before you buy

  1. 01
    Rust, everywhere, even in dry statesAutotrader Classics calls rust the biggest concern and warns that surface rust can hide serious rot. Check the rocker panels and the floor pans they join, the cargo floor (especially where it meets the half-cab wall), the door posts around the hinges, the firewall and inner fenders, the tailgate and the frame rails. Velocity Restorations notes that structural rust can cost more than it's worth to fix.
  2. 02
    Cut or uncut rear fendersMany early Broncos had their rear fenders cut to fit flares and bigger tires. Uncut trucks are rarer and worth more, and flared trucks sell for less. Look closely at the quarter panels for filler or patched-in arches.
  3. 03
    Frame at the steering boxWild Horses points out that the frame takes a lot of load where the steering box bolts on, and that area can weaken or crack. With the engine running, have someone turn the wheel and watch the box. If it moves on the frame, check for cracks before you buy.
  4. 04
    Does it drive straight?A wandering early Bronco usually has the wrong caster, according to Wild Horses, especially after a lift with the wrong C-bushings. Lean of 2 inches or more is common after a suspension change. Neither is expensive to fix, but both tell you how carefully the truck was built.
  5. 05
    VIN and data plateThe VIN is stamped on the frame rail, just ahead of the firewall under the engine, and the full data plate is inside the glovebox door. Check that they match the title. The first three characters give the series (U13, U14 or U15) and the fourth the engine code; a mismatch is common after decades of swaps, which matters most on a claimed original.
  6. 06
    Baja, Sport and Ranger claimsOnly 650 Baja Broncos were sold, and they now bring far more than a standard truck, so clones exist. Ask for documentation of any special edition. The data plate and VIN won't prove a Baja by themselves, so lean on build records and a marque specialist.
  7. 07
    Who built it?Most early Broncos for sale are modified, and many are full restomods. Velocity Restorations suggests asking what was done and by whom, whether there is documentation, whether the frame has been repaired or replaced, and how it drives at highway speed. A cheap build can cost more over time than a good one.
  8. 08
    Hard-to-find partsMechanical parts are easy because the trucks use common Ford engines and Dana axles. Autotrader notes that thin steel grilles dent easily and are often cut for plows or PTO gear, and good tailgates are also scarce. Price those in if they're bad.

Spotting the real thing

Most early Broncos have been modified, re-engined or re-bodied, and some are built on reproduction bodies and aftermarket frames. The frame VIN and the glovebox data plate are your starting points.

  1. ID
    VIN layoutEleven characters, such as U15GL followed by six serial digits. Positions 1–3 are the series: U13 roadster, U14 half-cab pickup, U15 wagon. Position 4 is the engine: F for the 170 six, S for the 200 six, N for the 289 and G for the 302. Position 5 is the plant, L for Michigan Truck. The model year is worked out from the serial range.
  2. ID
    Where to lookThe VIN is stamped on the frame rail under the engine, just ahead of the firewall; with the wheel turned fully right it can be seen from the wheel well. The full data plate is inside the glovebox door, with codes for paint, body, transmission, axle and sales district.
  3. ID
    Axle codeThe data plate's axle code gives the ratio and whether there's a limited-slip: CJ Pony's 1968 decoder lists 3.50, 4.11 and 4.57 ratios, with separate codes for the limited-slip versions. On the truck itself, the Dana 30 front has king pins and the Dana 44 has ball joints.
  4. ID
    Transfer-case shifterA straight up-and-down T-handle means a 1966–72 Dana 20 with a 2.46:1 low. A backward-J pattern means a 1973–77 case with 2.34:1. Rebuild parts differ between them.
  5. ID
    Front brakes and steeringFactory front discs and a Y-type tie rod mean 1976–77 hardware. Earlier trucks with discs have been converted. Many trucks of every year now carry aftermarket steering linkage.
  6. ID
    Special editionsBaja Broncos (650 sold) and other high-value trucks are worth faking, and the VIN alone won't prove one. Ask for build documentation and get a marque specialist to inspect it.

Recalls & service bulletins

Open recalls follow the VIN, not the model. Run yours through NHTSA before you buy, and ask the seller for dealer records showing recall work.

Check a VIN at NHTSA ↗
Notable recalls
Steering drag-link connection ↗1967 · NHTSA 66V026000Ford campaign filed November 1966 covering the drag-link connection.
Brake pedal and linkage ↗1967 · NHTSA 66V004003Ford campaign filed October 1966 covering the service-brake pedal and linkage.
Tires (tread / belt) ↗1970–1971 · NHTSA 70V113000Ford tire campaign filed September 1970.
Exhaust system ↗1975 · NHTSA 76V015000Ford campaign filed February 1976 covering the exhaust manifold, muffler and pipes.
Aftermarket mechanical fuel pumps (Federal-Mogul) ↗1975–1977 · NHTSA 07E064000Carter, Accuflow, NAPA and other-brand replacement pumps shipped August 2006–July 2007 may leak fuel from an improperly installed diaphragm.
The one you’ll own someday

For sale now

1966–1977 · USEarly Bronco (all)
AutoTempest ↗Bring a Trailer ↗
1966–1968 · USRoadster era (170 / 289)
AutoTempest ↗Bring a Trailer ↗
1969–1975 · US302 V8 years (incl. Baja Bronco)
AutoTempest ↗Bring a Trailer ↗
1976–1977 · USFactory front discs
AutoTempest ↗Bring a Trailer ↗
PART 04

Owning one

Baseline service, the repairs you’ll actually do, and where the manuals live.

Post-purchase baseline

After you buy it

Assume nothing has been done, and assume plenty has been changed: most early Broncos have been modified, so check what engine, axles and transfer case you actually have before buying parts. The data plate on the glovebox door gives the factory engine, transmission and axle codes.

Engine oil & filter302 V8 capacity [CONFIRM IN MANUAL] · the 1966 170 six has a 6-quart oil pan (Ford press release)At purchase, then per manual

Swapped engines are common. Check what's actually in the truck before ordering a filter.

Parts
RockAuto catalog, 1972 Bronco 302 — oil filtersRockAuto ↗
Search engine oil & filter for the Ford Bronco (1966–1977)Amazon ↗
Air filterPaper element on most trucks · early sixes had an oil-bath air cleanerInspect at every oil change

An oil-bath cleaner needs its reservoir cleaned and refilled with oil, not a new element.

Parts
RockAuto catalog, 1972 Bronco 302 — air filtersRockAuto ↗
Search air filter for the Ford Bronco (1966–1977)Amazon ↗
Spark plugs, cap, rotor & wiresPlug type and gap [CONFIRM IN MANUAL]At purchase

Points-type ignition is still common on unmodified trucks. Set dwell and timing afterward.

Parts
RockAuto catalog, 1972 Bronco 302 — spark plugsRockAuto ↗
RockAuto catalog, 1972 Bronco 302 — distributor capsRockAuto ↗
1966–73 289/302 8 mm spark plug wiresBronco Graveyard ↗ · Amazon ↗
Coolant, thermostat, hoses & water pumpCoolant type and capacity [CONFIRM IN MANUAL]Flush at purchase, then every 2 years

The stock Bronco V8 water pump has its inlet on the passenger side, which matters for pump and bracket fitment.

Parts
1966–77 Bronco thermostat housing kit, V8Bronco Graveyard ↗ · Amazon ↗
1966–77 Bronco V8 radiator hose kitBronco Graveyard ↗ · Amazon ↗
Water pump, V8 (passenger-side outlet), 1966–77Bronco Graveyard ↗ · Amazon ↗
BeltsFan and alternator belt; extra belt with power steeringAt purchase

Carry a spare on the trail.

Parts
1966–77 289/302 fan and alternator beltBronco Graveyard ↗ · Amazon ↗
Manual transmission (three-speed)Gear oil; ClassicBroncos owners use 75W-90 · grade and capacity [CONFIRM IN MANUAL]Change at purchase

Many trucks now have floor shifters or swapped four- and five-speeds. Identify the gearbox first.

Parts
Bronco three-speed manual transmission gasket kitBronco Graveyard ↗ · Amazon ↗
Automatic transmission (C4, 1973–77)ATF · type and capacity [CONFIRM IN MANUAL]Pan drop and new filter at purchase

Check the cable shift linkage for wear while you're under there.

Parts
1966–77 Bronco C4 cable shift linkageBronco Graveyard ↗ · Amazon ↗
Dana 20 transfer caseFactory spec was 50-weight motor oil (ClassicBroncos) · fill to the plugChange at purchase

Some owners avoid GL-5 gear oil because of its effect on brass and bronze parts. Look for leaks at the intermediate housing.

Parts
Dana 20 intermediate oil sealBronco Graveyard ↗ · Amazon ↗
Intermediate housing to Dana 20 gasketBronco Graveyard ↗ · Amazon ↗
Front & rear differentials (Dana 30/44, Ford 9-inch)Hypoid gear oil around 90 weight (75W-90/80W-90) · friction modifier for limited-slip · capacities [CONFIRM IN MANUAL]Change at purchase and after deep water

Factory ratios were 3.50, 4.11 and 4.57, some with limited-slip; the axle code on the data plate tells you which.

Parts
RockAuto catalog, 1972 Bronco 302 — drivetrainRockAuto ↗
Search front & rear differentials (dana 30/44, ford 9-inch) for the Ford Bronco (1966–1977)Amazon ↗
Front wheel bearings, hub seals & locking hubsRepack with wheel-bearing grease; new sealsAt purchase

Replace the hub seals whenever the inner bearing comes out. Check the locking-hub O-rings too.

Parts
1966–71½ wheel bearing and hub seal kitBronco Graveyard ↗ · Amazon ↗
Dana 44 locking hub O-rings, 1966–78 (set of 4)Bronco Graveyard ↗ · Amazon ↗
C-bushings, radius-arm & track-bar bushingsCaster +4° to +9° (Wild Horses)Inspect at purchase

Worn upper track-bar bushings are the top cause of shimmy. Make sure the C-bushings are the right way up.

Parts
C-bushing kit, 7°, 1966–75Bronco Graveyard ↗ · Amazon ↗
Radius-arm bushing washer set, 1966–79Bronco Graveyard ↗ · Amazon ↗
Brake fluid, hoses & linesFluid type [CONFIRM IN MANUAL]Flush at purchase, then every 2 years

Replace old rubber hoses and rusty rear axle lines.

Parts
1967–75 Bronco front brake hose kit (set of 4)Bronco Graveyard ↗ · Amazon ↗
1966–77 Bronco rear axle brake lines, stainless (pair)Bronco Graveyard ↗ · Amazon ↗
Fuel pump, filter & sending unitMechanical pump; in-tank sending-unit filterAt purchase

On vacuum-wiper trucks the wiper vacuum comes through the fuel pump. Replace cracked rubber fuel hose.

Parts
1966–77 Bronco V8 fuel pump (289/302/351W)Bronco Graveyard ↗ · Amazon ↗
1966–77 Bronco sending-unit filterBronco Graveyard ↗ · Amazon ↗
RockAuto catalog, 1972 Bronco 302 — fuel filtersRockAuto ↗
Factory shop manualFord truck shop manuals on CD (1966 and 1977 editions listed)Once

Worth having for torque specs, capacities and adjustment procedures.

Parts
1966 Ford Bronco & truck shop manual (CD)Bronco Graveyard ↗ · Amazon ↗
1977 Ford truck shop manual, 3 volumes (CD)Bronco Graveyard ↗ · Amazon ↗
For the hands-on owner

Common repairs

The jobs owners actually end up doing, rated for a competent home mechanic with a decent tool kit. Always confirm torque figures, fluids and procedures against the factory service manual for your VIN, and work safely — support the truck on stands, never just a jack. You do this work at your own risk; see the disclaimer. Some parts links are affiliate links.

Floor pan, rocker and door-post rust repair
DIFFICULTY · 4 / 5TIME · ≈ Several weekends, depending on how far it goesSHOP COST · Parts plus welding labor; full floor and platform sets cost several hundred dollars
SYMPTOMSHoles or soft spots in the floor, bubbling along the rockers, sagging doors that won't latch cleanly, rust around the door-post hinges and water on the floor after rain.
THE FIXStrip the interior and probe every seam with a pick. Brace the door openings before cutting anything structural, then cut back to clean metal. Reproduction floor pans come with the grooves and body-mount recesses, and the floor channel support rails underneath are sold separately; replace them if they've gone. Fit inner and outer rockers and front door posts as needed, check door gaps before final welding, then seam-seal and coat the new metal. If the firewall, inner fenders or frame rails are also rotten, Autotrader and Velocity both warn that the bill can outrun the truck's value.
TOOLS & PARTSMIG welder · cut-off wheel and spot-weld drill · door-opening braces and clamps · seam sealer and weld-through primer
WHERE TO BUY PARTS1966–77 Bronco floor pans with grooves and body-mount recess (pair) · Bronco Graveyard ↗Amazon ↗1966–77 Bronco OEM steel rocker panel · Bronco Graveyard ↗Amazon ↗1968–77 Bronco left inner rocker panel · Bronco Graveyard ↗Amazon ↗1966–77 Bronco front door posts (pair) · Bronco Graveyard ↗Amazon ↗
Front disc brake conversion (1966–75)
DIFFICULTY · 3 / 5TIME · ≈ A daySHOP COST · Kits $675 (Bronco Graveyard, with proportioning valve and bracket) to $849.99 (Wild Horses)
SYMPTOMSFading, pulling or long stops from the original four-wheel drums, especially on bigger tires. 1976–77 trucks already have factory power front discs.
THE FIXJack up the front and remove the wheels, locking hubs, drums and the drum-brake spindles. Wild Horses' kit fits 1966–early 1971 Dana 30 and 1971–75 Dana 44 axles with six-bolt drum knuckles, and includes disc spindles, caliper brackets, calipers and pads, hub-and-rotor assemblies and new wheel bearings. Bolt on the new spindles and brackets, pack and fit the bearings in the new hubs, and set the bearing preload. Fit new caliper hoses and a proportioning valve for disc-front, drum-rear brakes, then bleed the system. Wild Horses recommends aftermarket locking hubs such as Warn or Mile Marker, and buyers suggest doing the outer axle seals and U-joints and adding a brake booster at the same time.
TOOLS & PARTSSpindle-nut socket · bearing packer and seal driver · flare-nut wrenches · brake bleeder
WHERE TO BUY PARTSFront disc brake conversion kit, Dana 30 & Dana 44, 1966–75 Bronco · Wild Horses 4x4 ↗Amazon ↗1966–75 Bronco front disc brake conversion kit with proportioning-valve bracket · Bronco Graveyard ↗Amazon ↗1966–77 Bronco proportioning valve, disc front / drum rear · Bronco Graveyard ↗Amazon ↗1966–77 Bronco power brake booster · Bronco Graveyard ↗Amazon ↗
Fix wandering and lean: caster, C-bushings and track-bar bushings
DIFFICULTY · 3 / 5TIME · ≈ Half a day to a daySHOP COST · Parts about $100–150 (C-bushing kit plus track-bar bushings)
SYMPTOMSThe truck darts and wanders on the highway, needs constant correction, shimmies after bumps, or sits visibly lower on one side at the front.
THE FIXWild Horses says about 90 percent of wandering early Broncos have incorrect caster, and its spec is +4 to +9 degrees. Lifting the truck moves caster negative, which is why offset C-bushings exist; 7 degrees is the standard. Support the frame on stands (not the axle), unbolt the radius-arm caps and fit the new C-bushings the right way up, following the 'front bottom' and 'rear bottom' markings. A bushing installed upside down changes caster and can make the truck lean. If it still leans, Brian Cooke's fix is to check that both radius arms touch a level floor at the same time and reseat the C-bushings by retightening the cap bolts in a different order. For shimmy and death wobble, Wild Horses names worn upper track-bar bushings as the number one culprit.
TOOLS & PARTSJack stands under the frame · floor jack · socket set and torque wrench · angle finder for caster
WHERE TO BUY PARTSC-bushing kit, 7°, 1966–75, 14 pieces · Bronco Graveyard ↗Amazon ↗C-bushing kit, 7°, 1976–77, 14 pieces · Bronco Graveyard ↗Amazon ↗Track-bar bushings, 1966–75 · Bronco Graveyard ↗Amazon ↗Track-bar bushings, 1976–77 · Bronco Graveyard ↗Amazon ↗
Front-end rebuild: ball joints (or king pins), wheel bearings and spindle seals
DIFFICULTY · 3 / 5TIME · ≈ A day for both sidesSHOP COST · Ball joints $38.99 per side (Wild Horses); bearing and seal kits extra
SYMPTOMSLoose or sloppy steering, wander and uneven tire wear. With the front jacked up, the wheel rocks when you grip it at the top and bottom.
THE FIXDana 44 axles (mid-1971 on) use upper and lower ball joints; earlier Dana 30s use king pins with tapered bearings instead. On a Dana 44, remove the hub, bearings and spindle and slide out the axle shaft. Owners on ClassicBroncos remove the castle nut, unscrew the upper ball joint's adjusting bushing with a spanner tool, then separate the knuckle with a pickle fork, alternating taps top and bottom. Press out the old joints and press in the new ones, keeping the upper grease fitting accessible. While it's apart, replace the spindle bearing and seal and the axle-stub slinger and seal, fit new hub seals with the inner bearings, and consider new axle U-joints. Pack the wheel bearings and set the preload.
TOOLS & PARTSBall-joint press (rentable) · Dana 44 ball-joint spanner · pickle fork · brass drift · spindle-nut socket
WHERE TO BUY PARTSDana 44 upper and lower ball joints (one side), 1971–77 Bronco · Wild Horses 4x4 ↗Amazon ↗Dana 30 king-pin bearing and race (Timken) · Bronco Graveyard ↗Amazon ↗1966–71½ wheel bearing and hub seal kit · Bronco Graveyard ↗Amazon ↗RockAuto catalog, 1972 Bronco 302 — ball joints · RockAuto ↗
Steering box mount, play adjustment and power-steering conversion
DIFFICULTY · 3 / 5TIME · ≈ A day for a conversion; more if the frame needs weldingSHOP COST · Bronco Graveyard's complete Delphi conversion is $1,199
SYMPTOMSSteering play, a box that shifts on the frame when the wheel is turned, cracks in the frame around the box, or heavy manual steering (manual was standard through 1972).
THE FIXCheck the box is tight to the frame first: a loose box moves and makes the steering feel vague. Inspect the frame rail around the mounting bolts and, as Wild Horses suggests, weld in extra support if it's cracked or thin. Never turn the play-adjusting screw on top of the box more than one turn in, or the sector shaft jams against the piston. To add power steering, you need double-groove crank and water-pump pulleys, a pump bracket and a pump. On trucks with vacuum wipers fed from the fuel pump, the pump can't go in its normal place, so convert to electric wipers first. Bronco Graveyard's Delphi kit has a 3.75-turn box that bolts on with the three stock bolts (a fourth hole can be drilled), plus the pump, hoses, pulleys and a collapsible lower shaft for a 3/4-inch 36-spline aftermarket column.
TOOLS & PARTSPitman-arm puller · socket set and torque wrench · welder and grinder (if the frame is cracked) · drill
WHERE TO BUY PARTS1966–77 Bronco Delphi power-steering conversion, 3.1:1 ratio (V8) · Bronco Graveyard ↗Amazon ↗Delphi power-steering box, 1966–77 Bronco · Bronco Graveyard ↗Amazon ↗Early Bronco tie rods and drag links · Wild Horses 4x4 ↗Amazon ↗RockAuto catalog, 1972 Bronco 302 — tie rod ends · RockAuto ↗
Dana 20 transfer case leaks and rebuild
DIFFICULTY · 4 / 5TIME · ≈ A weekendSHOP COST · Master bearing and seal kits $109–125 (Bronco Graveyard)
SYMPTOMSOil weeping from the case or the joint with the transmission's intermediate housing, gear whine, jumping out of range, or a stiff shift.
THE FIXWork out which case you have before ordering. Wild Horses notes that 1966–72 cases use a T-handle with a 2.46:1 low range and 1973–77 cases a J-shift with 2.34:1, and the front output, bearings, shift rails and detents differ. Drain the case, disconnect both driveshafts, the speedometer cable and the shift linkage, and unbolt the case from the intermediate housing. Replace the bearings, seals and gaskets; a deluxe kit adds a new cluster shaft, thrust washers and shims. Fit a new intermediate seal and gasket, reinstall, and fill to the plug. ClassicBroncos regulars say Ford specified 50-weight motor oil for the Dana 20, and some warn that GL-5 additives can harm its brass and bronze parts.
TOOLS & PARTSDrain pan · snap-ring pliers · bearing puller and press · seal drivers · torque wrench
WHERE TO BUY PARTSDana 20 master bearing and seal kit, 1966–72 (T-handle) · Bronco Graveyard ↗Amazon ↗Dana 20 master bearing and seal kit, 1973–77 (J-shift) · Bronco Graveyard ↗Amazon ↗Dana 20 intermediate oil seal · Bronco Graveyard ↗Amazon ↗Intermediate housing to Dana 20 gasket, 1966–77 · Bronco Graveyard ↗Amazon ↗
Vacuum wipers to electric (1966–69)
DIFFICULTY · 2 / 5TIME · ≈ Half a daySHOP COST · Parts plus your time
SYMPTOMSWipers that slow down or stop when you accelerate uphill, the classic vacuum-wiper failure, or a vacuum-wiper fuel pump blocking a power-steering pump.
THE FIXFord switched from vacuum to electric wipers in mid-1969, and on the early trucks the vacuum supply runs through the fuel pump. Remove the vacuum motor and its lines, fit the electric motor and bracket on the windshield frame, connect the motor arm to the existing linkage and run the wiper harness to a switch. An electric-wiper cover finishes the job. Replace the fuel pump with a non-vacuum V8 pump while you're there, which also frees up the spot a power-steering pump needs.
TOOLS & PARTSScrewdrivers and sockets · drill · wire strippers and crimpers · test light
WHERE TO BUY PARTS1966–77 Bronco electric wiper motor · Bronco Graveyard ↗Amazon ↗1969–77 Bronco wiper motor wiring harness · Bronco Graveyard ↗Amazon ↗Wiper linkage motor arm for electric wipers, 1966–77 · Bronco Graveyard ↗Amazon ↗1966–77 Bronco V8 fuel pump (289/302/351W) · Bronco Graveyard ↗Amazon ↗

Manuals & documentation

1966 Ford Bronco & truck shop manual (CD) ↗Reprint factory manual from Bronco Graveyard1977 Ford truck shop manual, 3 volumes (CD) ↗Reprint factory manual covering the last early BroncosBronco Graveyard — technical diagrams archive ↗Exploded parts diagramsCJ Pony Parts — Bronco VIN decoders by year ↗Data-plate code tables (series, engine, axle, paint, build month)Wild Horses — 1966 Bronco launch press releases ↗Ford's original August 1965 specifications
Asked on every forum

Ford Bronco (1966–1977) questions, answered

What's the biggest tire I can fit without a lift?

On an uncut truck at stock height, Performance Plus Tire calls 30x9.50R15 the safe choice and says 31x10.50R15 may lightly rub at full stuff or full lock. ClassicBroncos owners agree: 235/75R15 bolts on, and a few squeeze 33x9.50s on with fender trimming and some rubbing. For 31–32-inch tires on uncut fenders, plan on a 2–3-inch lift and 3.75–4.25 inches of wheel backspacing; 33x12.50s generally mean cut fenders.

SOURCE · PERFORMANCE PLUS TIRE · CLASSICBRONCOS
Does mine have a Dana 30 or a Dana 44 front axle?

Ford switched from the Dana 30 to the stronger Dana 44 partway through the 1971 model year. A quick tell is the knuckle: Wild Horses notes the Dana 30 uses king pins, while the Dana 44 uses ball joints. Every first-generation Bronco has a Ford 9-inch rear axle.

SOURCE · AUTOTRADER CLASSICS · WILD HORSES
Which engine should I look for?

Most buyers want a V8. The 289 arrived in March 1966 and was replaced by the 302 for 1969, which ran to 1977; CJ Pony Parts lists the 1975 302 at 125 hp net. The sixes are the 170 (105 hp at launch) and, from 1973, the 200. Plenty of trucks now have swapped engines, from 351 Windsors to modern Coyote V8s.

SOURCE · WIKIPEDIA · CJ PONY PARTS
How do I read the VIN?

An early Bronco VIN is 11 characters, such as U15GLxxxxxx. U13 is the roadster, U14 the half-cab pickup and U15 the wagon. The fourth character is the engine (F for the 170 six, N for the 289, G for the 302) and the fifth the plant (L for Michigan Truck). The VIN is stamped on the frame rail ahead of the firewall, and the data plate is inside the glovebox door.

SOURCE · CJ PONY PARTS · BRONCOZONE
Why does my Bronco wander?

Wild Horses says about 90 percent of wandering early Broncos have incorrect caster. The spec is +4 to +9 degrees, and lifting the truck moves it negative. Offset C-bushings (7 degrees is standard) bring it back, and taller lifts may need drop brackets or long radius arms. For shimmy and death wobble, check the upper track-bar bushings first.

SOURCE · WILD HORSES
Does it have front disc brakes?

Only 1976–77 Broncos came with power front disc brakes from the factory. Earlier trucks have drums all round, and conversion kits for 1966–75 Dana 30 and Dana 44 axles are widely available. Wild Horses' kit uses new spindles, brackets, calipers and hub-and-rotor assemblies.

SOURCE · AUTOTRADER CLASSICS · WILD HORSES
Did it come with power steering?

Manual steering was standard through 1972, and power steering was optional from 1973. According to Wild Horses, 1973–75 power boxes take about six turns lock to lock and 1976–77 boxes about four. Many owners convert to a modern Delphi box; Bronco Graveyard's kit has 3.75 turns lock to lock.

SOURCE · WILD HORSES · BRONCO GRAVEYARD
What oil goes in the Dana 20?

ClassicBroncos regulars say Ford specified 50-weight motor oil for the Bronco's Dana 20, filled until it runs out of the fill plug. Some owners use synthetic manual-transmission fluid or 75W-90 gear oil instead, and some warn that GL-5 additives can harm the case's brass and bronze parts.

SOURCE · CLASSICBRONCOS
What's a Baja Bronco?

A package designed by Bill Stroppe and sold through Ford dealers from 1971, with an automatic, quick-ratio power steering, fender flares over Gates Commando tires, a roll bar, reinforced bumpers and red, white, blue and black paint. It cost $5,566 against $3,665 for a standard V8 Bronco, and only 650 were sold in four years. Insist on documentation.

SOURCE · WIKIPEDIA
Are uncut fenders worth paying for?

Yes, if originality matters to you. Many trucks had their rear fenders cut for flares and bigger tires, so uncut ones are rarer and bring more money, and flared trucks sell for less. If you plan to run 33s or bigger anyway, a well-done cut truck can save you money.

SOURCE · AUTOTRADER CLASSICS
What are they worth?

A lot, and it depends on who built it. Of 306 complete early Broncos sold on Bring a Trailer between August 2025 and October 2026, the middle half of stock and mildly modified trucks sold for about $41,500–70,000, with a median near $55,500. Projects mostly went for $9,600–37,000, and Coyote-swapped and shop-built restomods for about $122,000–166,500, topping out at $325,000. Hagerty recorded a 12 percent drop in the second quarter of 2026, but says a driver still costs $50,000 or more.

SOURCE · BRING A TRAILER · HAGERTY
PART 05

Building one

Who makes the good stuff, where owners gather, and who to watch.

Common modifications & who does them

SUSPENSION LIFTNew coils and leaf springs undo decades of sag, and a 2.5–3.5-inch lift clears 31–33-inch tires. Match the C-bushings to the lift height so caster stays positive.
Wild Horses — early Bronco 4-inch suspension lift kit ↗Bronco Graveyard — 2.5-inch standard lift kit (1966–75) ↗James Duff — Bronco suspension catalog ↗
STEERINGBigger tires overwhelm the stock linkage, and the 1976–77 Y-link bends. Heavier adjustable tie rods and a modern power box make it track straight.
Wild Horses — custom tie rods and drag links ↗Bronco Graveyard — Delphi power-steering conversion ↗
BRAKESFour-wheel drums on a truck with 33s is optimistic. Disc conversions and a better booster are the first real-world upgrade on 1966–75 trucks.
Wild Horses — front disc brake conversion kits ↗Bronco Graveyard — Extreme power brake booster setup ↗
AXLES & LOCKERSThe Dana 44 and 9-inch are strong, but bigger tires break axle shafts and an open diff stalls on rocks. Chromoly shafts and a locked 9-inch third member are the usual fixes.
Bronco Graveyard — Yukon chromoly Dana 44 axle set with U-joints ↗Bronco Graveyard — Ford 9-inch third member with Grizzly locker ↗
DRIVETRAIN SWAPS & COOLINGFive-speed manuals and modern V8s are the restomod staples. An aluminum radiator helps any V8 survive slow trails.
Bronco Graveyard — AX15 five-speed swap kit ↗Ford Performance Parts — crate engines ↗Bronco Graveyard — aluminum high-efficiency radiator, V8 ↗
RESTOMOD BUILDERSIf you'd rather write a check than weld, these shops build turn-key early Broncos, and their trucks dominate the top of the auction results.
ICON 4x4 — BR ↗Gateway Bronco ↗Velocity Restorations ↗Maxlider Brothers Customs ↗

Clubs & events

CLUB Early Bronco Registry ↗Nationwide early Bronco registry founded in 1991 by members of Early Broncos Limited (1981), with more than 6,000 members.EVENT Bronco Daze 2026 ↗Early Bronco Registry's 60th-anniversary gathering, November 13–15, 2026, Borrego Springs, California; billed as the last Bronco Daze.CLUB Utah Bronco Club ↗Volunteer-run Utah nonprofit for Bronco owners, focused on trail stewardship and responsible off-roading.
Resources

Channels, accounts & forums

All Bronco resources →
YouTube channels
YTWild Horses Off-Road1966–77 BRONCO TECH & TRAILYTTheBroncoGraveyardBRONCO PARTS & INSTALLSYTJamesDuffIncBRONCO SUSPENSION SINCE 1967YTGateway BroncoCLASSIC BRONCO RESTOMODSYTMaxlider Bros.EARLY BRONCO BUILDSYTVelocity RestorationsRESTOMOD BUILDS
Instagram accounts
IG@wildhorsesbroncosEARLY BRONCO PARTS & BUILDSIG@gatewaybroncoCLASSIC BRONCO BUILDSIG@icon4x4ICON BR BUILDSIG@maxlidermotorsEARLY BRONCO RESTOMODSIG@velocityrestorationsRESTOMOD BUILDS
Forums & message boards
ClassicBroncos.com forums ↗The deepest 1966–77 tech archive: tire fitment, steering, Dana 20, rust repairBronco Zone — 1st Gen: 1966–1977 Early Bronco ↗General early-Bronco discussionBronco Zone — 66–77 Early Bronco Tech Support ↗Tech questions, including VIN and data-plate decoding
SourcesWikipedia — Ford BroncoAutotrader Classics — 1966–77 Ford Bronco collector's guideWild Horses 4x4 — 1966 Ford Bronco announcement publicity releasesVelocity Restorations — Ultimate guide to buying a classic Ford BroncoHagerty — Vintage Ford Bronco values: a breakdown by generationFord Authority — First-gen Ford Bronco values may finally be heading back down to earth (July 2026)Bring a Trailer — Ford Bronco U13/U14/U15 1966–1977 auction resultsMotor Authority — Parnelli Jones' Big Oly Bronco sells for $1.87MSports Car Digest — Big Oly Ford BroncoWild Horses 4x4 — Early Bronco Dana 20 transfer caseWild Horses 4x4 — How to stop your early Bronco from wanderingWild Horses 4x4 — How to fix early Bronco leanWild Horses 4x4 — Steering techWild Horses 4x4 — Early Bronco custom steering linkage upgradesWild Horses 4x4 — Front disc brake conversion kit, 1966–75 BroncoWild Horses 4x4 — Dana 44 upper and lower ball joints, 1971–77 BroncoBronco Graveyard — 1966–77 Bronco Delphi power-steering conversionCJ Pony Parts — 1968 Bronco VIN decoderCJ Pony Parts — 1975 Bronco VIN decoderBronco Zone — VIN number / warranty plate decode informationPerformance Plus Tire — Early Bronco wheels and tires: the 1966–1977 fitment guideClassicBroncos — What's the largest tire you can run on an uncut stocker?ClassicBroncos — Transfer case oil changeClassicBroncos — Transfer case and axle fluid recommendationsClassicBroncos — Replacing ball joints, bearings and sealsAutotrader Classics — 1966–77 Ford Bronco collector's guideWikipedia — Ford BroncoWild Horses 4x4 — 1966 Ford Bronco announcement publicity releasesWild Horses 4x4 — Early Bronco Dana 20 transfer caseWild Horses 4x4 — Steering techWild Horses 4x4 — How to stop your early Bronco from wanderingCJ Pony Parts — 1968 Bronco VIN decoderCJ Pony Parts — 1975 Bronco VIN decoderCJ Pony Parts — Ford Bronco bolt patterns by generationBronco Zone — VIN number / warranty plate decode informationPerformance Plus Tire — Early Bronco wheels and tires: the 1966–1977 fitment guideClassicBroncos — What's the largest tire you can run on an uncut stocker?NHTSA recalls API — Ford Bronco 1966–1977Bring a Trailer — Ford Bronco U13/U14/U15 1966–1977 auction resultsHagerty — Vintage Ford Bronco values: a breakdown by generationFord Authority — First-gen Ford Bronco values may finally be heading back down to earth (July 2026)Early Bronco Registry — home and Bronco Daze 2026Bronco Graveyard — shop manuals and technical diagrams