this noise has me stumped

this is the wierdest noise ive ever heard. it is a loud squeak that has the consistency of a chatter (squeak squeak squeak) not a constant noise. its coming from the rear end from what i can tell. only happens under load in forward only not reverse, not during cruise. also must be a heavy load, like a 1-2 downshift or moderate to heavy throttle from a stop. thought the exhaust was touching the driveshaft, but changed the mounting of the muffler to no avail. this noise is LOUD and very very annoying. im starting to wonder if its a bad bearing in the diff or possibly a wheel bearing, maybe even shot gears (some idiot put them in before i got the axle). any ideas to narrow this down would be appreciated.

92 xj, 4.0L aw4 8.25rear 4.56 ratio

Sounds like a bad U-joint .

Nick

i was thinking that too but i cant find any play and the driveshaft seems to spin fine with no binding. i suppose they could be rusting out i dont think ive ever replaced the rears now that i think about it...

i'd say start with u joints.... if you have never replaced them nows a good time and you might lucky. beats having to change them on the side of the freeway...