Just reached the 250,000 mile (402336 kilometers) mark on my 91 Wrangler.
Performed a compression check and all cylinders reading 155 Psi. Leakdown
test showed all cylinders and valves are still tight. Drivetrain is all
orignal, so same mileage all around on driveline components. Only major
driveline maintenance:
replaced Dana 30 DS front axle: Moab incident (first and only trail
breakdown).
replaced Dana 35 outside axle seals and differential gears (spiders).
replace tracloc clutch pack.
replaced AX15 bearings and 2d & 3rd sychros.
replaced clutch, pressure plate and TO bearing.
replaced internal slave twice (needs another one)
replaced NP231 chain (ran dry), didn't change the gears though.
replaced rear Ujoints (several times).
replaced rear pinion and seal twice.

Jeep is a 91YJ 4.0L six with header and HiPro cam.
4" Skyjacker lift with BFG 33X12.5 MT
original Dana front and rear diffs with 4.10 gearing.
various other mods too numerous to mention here.

This has been one dam fine YJ.

Scott