bad u-joint on FRPP AL driveshaft

A bad u-joint would be easy to identify when the car is on a lift by twisting the driveshaft back and forth by hand and listening for the noise. If it doesn't move,then no bad u-joint. You could have a stack up of tolerances in the rear end. Have you had any rear end work done recently?

Can't hurt to double check all the tranny mount bolts and rear control arms bolts as well.

i thought i was having the same issue... found my UCA bushings were RAPED, 1/4-1/2" movement... scary... 1 way to check BOTH the UCAs AND the U joint in the same movement. jack the back end up (higher the better) get a friend (anyone) and a tire iron (i used mine from my mustang). put the tire iron on one of your lug nuts so its pointing up and down. put the car into 3rd gear (any forward gear is fine) and the E-brake off. while you rae under the car, have someone push and pull (harder the better) on the tire iron to force the wheels to rotate (of course the tranny being in gear will prevent it from turning).

the things to look for are a spread out so it might take a bit of time. the first is to make sure the long part of the driveshaft is not moving. if it does move then you might have more problems. if its the U joints then the main shaft will be stationary, but the back part after the U joint will move when the person is yanking on the iron.

for the UCAs... you can alter this slightly by jacking the E brake and doing the same thing... this will force the axle to try and rotate if it does rotate slightly then look for the weak point. there are only 4 places of connection (2 LCA, 2 UCA) so it HAS to be one of them.. just look for where it is. also note... both control arm type have 2 ends.. so you will have to look at both the axle end and the chasis end bushings to make sure none are giving way. to make note, there might be a SINGLE bushing moving, so look at all 8 bushings individually.

hope it has helped.

Torinalth

checked your TQ box lately?