Symptoms
Wet carpet, rusty seat-bracket bolts, holes under the mats, crumbling rockers, and rust at the rear cab bulkhead where the bed meets the cab.
The fix, step by step
- Strip the cab, cut out the rot to clean metal, and treat what you can't cut.
- Trial-fit the panels, then plug- or stitch-weld them in.
- On a unibody, the floor and rockers are structural, so don't rely on screwed-in tin.
- Seam-seal, paint and wax the cavities.
- Fix the leak that caused it, usually the rear window and bulkhead seals.
- If the rails under the cab are swollen with rust, the job is much bigger.
Tools & part numbers
- MIG welder
- cut-off wheel
- spot-weld drill
- clamps
- weld-through primer
- seam sealer
- cavity wax
Where to buy the parts
Key Parts rocker panel replacement, 1986–92 Comanche MJQuadratec ↗Amazon ↗
Key Parts inner rocker panel, Comanche MJQuadratec ↗Amazon ↗
Key Parts front floor pan, 1984–2001 XJ (the MJ cab is XJ forward of the B-pillar; confirm fit)Quadratec ↗Amazon ↗
Hunting a used or discontinued part? Search eBay Motors for Jeep Comanche MJ parts →
Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.