Ok, I read all through the archives and still cannot come up with an answer. I just put a T5 in my car (was auto) and now every time I shift there is a harsh clunk coming from the rear of the car. It also repeadely clunks when u let off the throttle in 4'th or 5'th gear and the rpm's are low. I KNOW it is not the trans mount, because I have a spohn torque arm and a brand new poly mount. So i'm thinking (hoping) it's either the u-joints at the rear or the rear itself. I have a 3.23 locking posi, just put synthetic fluid in it not too long ago. Anyone have any ideas?? What do u have to do to check the u-joints?? All help is appreciated. Thanks

 

ujoints if worn out will be physically loose when you grab hold of driveshaft and try to move it around, also check your torque arm and rmount out, its gotta be one or the other problem

 

I second the ujoints and check the trans mount as well.