About to buy an XJ, need help!

[FriscoCHL]

Not to be an ass about it, but that's a strange question for someone to ask who said they work on cars for living. If they don't match, the front and rear axles will be turning at different speeds which will cause things to go boom when it's in 4wd.

Let me clarify. I/we do mostly brakes and undercar stuff (exhaust, struts, shocks, front end and suspension repair). While we do engine repairs. We do not do driveline work, with exception of u-joints here and there and CV/ half shafts. With the exception of a Z71/FX4 or an AWD escalade or navigator, we deal with or even see VERY little 4x4 stuff. There for I know nothing about 4x4 driveline stuff especially modified ones. hints my OP question about the rear end of this xj.

ETA: and no i do not work at just brakes...