Specs, fluids & service · 1966–1977

Ford Bronco (1966–1977) specs, fluids and service intervals

The numbers you need in the garage, on one page: spec sheet, capacities and service intervals, wheels and tires, and the parts to order. Sourced from owners, specialists and the factory; tags marked confirm in manual haven't been checked against a factory source yet.

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Spec sheet

BUILT	Michigan Truck Plant, Wayne, Michigan · 1965–1977
PRODUCTION	≈ 225,600 (Autotrader Classics)
BODIES	U13 roadster (to 1968) · U14 half-cab (to 1972) · U15 wagon
CHASSIS	Box-section ladder frame, unique to the Bronco
WHEELBASE	92 in · length 151.5 in
ENGINES	170 & 200 I6 · 289 & 302 V8
TRANSMISSIONS	3-speed manual (column shift) · C4 3-speed auto from 1973
TRANSFER CASE	Dana 20 · 2.46:1 low (T-handle) / 2.34:1 (J-shift)
FRONT AXLE	Dana 30 to mid-1971 · Dana 44 after; coil springs, radius arms
REAR AXLE	Ford 9-inch on leaf springs
BRAKES	Drums · power front discs 1976–77
TURNING CIRCLE	34 ft curb to curb (Ford, 1965)

By year

YEARS	PLATFORM	ENGINE	OUTPUT	NOTES
1966–1968	U13 roadster · U14 half-cab · U15 wagon	170 I6 · 289 V8 (from March 1966)	170: 105 hp · 289: 200 hp	Column-shift three-speed only. Sport package from 1967. The roadster was dropped after 1968.
1969–1972	U14 half-cab · U15 wagon	170 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.
1973–1975	U15 wagon	200 I6 · 302 V8	302 (1975): 125 hp net	C4 automatic and power steering optional from 1973; J-shift Dana 20 with 2.34:1 low.
1976–1977	U15 wagon	200 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.

Fluids, capacities & service intervals

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.

ITEM	SPEC / CAPACITY	INTERVAL	NOTES & PARTS
Engine oil & filter	302 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.RockAuto catalog, 1972 Bronco 302 — oil filters · RockAuto ↗
Air filter	Paper element on most trucks · early sixes had an oil-bath air cleaner	Inspect at every oil change	An oil-bath cleaner needs its reservoir cleaned and refilled with oil, not a new element.RockAuto catalog, 1972 Bronco 302 — air filters · RockAuto ↗
Spark plugs, cap, rotor & wires	Plug type and gap confirm in manual	At purchase	Points-type ignition is still common on unmodified trucks. Set dwell and timing afterward.RockAuto catalog, 1972 Bronco 302 — spark plugs · RockAuto ↗RockAuto catalog, 1972 Bronco 302 — distributor caps · RockAuto ↗1966–73 289/302 8 mm spark plug wires · Bronco Graveyard ↗
Coolant, thermostat, hoses & water pump	Coolant 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.1966–77 Bronco thermostat housing kit, V8 · Bronco Graveyard ↗1966–77 Bronco V8 radiator hose kit · Bronco Graveyard ↗Water pump, V8 (passenger-side outlet), 1966–77 · Bronco Graveyard ↗
Belts	Fan and alternator belt; extra belt with power steering	At purchase	Carry a spare on the trail.1966–77 289/302 fan and alternator belt · Bronco Graveyard ↗
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.Bronco three-speed manual transmission gasket kit · Bronco Graveyard ↗
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.1966–77 Bronco C4 cable shift linkage · Bronco Graveyard ↗
Dana 20 transfer case	Factory spec was 50-weight motor oil (ClassicBroncos) · fill to the plug	Change 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.Dana 20 intermediate oil seal · Bronco Graveyard ↗Intermediate housing to Dana 20 gasket · Bronco Graveyard ↗
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.RockAuto catalog, 1972 Bronco 302 — drivetrain · RockAuto ↗
Front wheel bearings, hub seals & locking hubs	Repack with wheel-bearing grease; new seals	At purchase	Replace the hub seals whenever the inner bearing comes out. Check the locking-hub O-rings too.1966–71½ wheel bearing and hub seal kit · Bronco Graveyard ↗Dana 44 locking hub O-rings, 1966–78 (set of 4) · Bronco Graveyard ↗
C-bushings, radius-arm & track-bar bushings	Caster +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.C-bushing kit, 7°, 1966–75 · Bronco Graveyard ↗Radius-arm bushing washer set, 1966–79 · Bronco Graveyard ↗
Brake fluid, hoses & lines	Fluid type confirm in manual	Flush at purchase, then every 2 years	Replace old rubber hoses and rusty rear axle lines.1967–75 Bronco front brake hose kit (set of 4) · Bronco Graveyard ↗1966–77 Bronco rear axle brake lines, stainless (pair) · Bronco Graveyard ↗
Fuel pump, filter & sending unit	Mechanical pump; in-tank sending-unit filter	At purchase	On vacuum-wiper trucks the wiper vacuum comes through the fuel pump. Replace cracked rubber fuel hose.1966–77 Bronco V8 fuel pump (289/302/351W) · Bronco Graveyard ↗1966–77 Bronco sending-unit filter · Bronco Graveyard ↗RockAuto catalog, 1972 Bronco 302 — fuel filters · RockAuto ↗
Factory shop manual	Ford truck shop manuals on CD (1966 and 1977 editions listed)	Once	Worth having for torque specs, capacities and adjustment procedures.1966 Ford Bronco & truck shop manual (CD) · Bronco Graveyard ↗1977 Ford truck shop manual, 3 volumes (CD) · Bronco Graveyard ↗

Capability

Wheelbase	92 in (2,337 mm)
Length	151.5 in (3,848 mm)
Turning circle	34 ft (10.4 m) curb to curb Ford launch release, 1965
Fuel tank	14.4 gal main + 8 gal auxiliary (1977) Capacities varied by year; an 11.5-gal auxiliary tank was optional from 1967
Transfer-case low range	2.46:1 (1966–72) · 2.34:1 (1973–77)
Engine output	170 I6: 105 hp · 289 V8: 200 hp · 302 V8 (1975): 125 hp net
Pickup box (half-cab)	32.8 cu ft Ford launch release

Wheels & tires

Factory tire	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 pattern	5x139.7 (5x5.5")
Biggest tire · Stock	30x9.50R15
Biggest tire · 2–3 in	31x10.50R15 (up to 32 in)
Biggest tire · 2–4 in, cut fenders	33x12.50R15
Biggest tire · Bigger lift plus body work	35x12.50R15

Open the Ford Bronco (1966–1977) in the tire fitment tool →

Common Ford Bronco (1966–1977) repairs

Always confirm torque figures, fluids and capacities against the factory service manual for your VIN. See the disclaimer; some parts links are affiliate links.