another vote for tranny mount...been there on my old '94 T/A. IT's easy to check...just use a jack like a previous person suggested...when you start to jack up the back of the tranny you should clearly see whether the rubber is seperated or not.

 

Okay, well how do I check if the torque arm has malfunctioned? When I replace the torque arm, do I have to take off the tranny mount first?

 

The torque arm is held on by a rubber C-clamp at the rear of the tranny. It should not be hard to identify whether it's messed up. It will likely NOT be held down by the clamp...you can always try just pushing it up and down...you shouldn't be able to move the thing at all. Once you are under your car and looking at things this will make a lot more sense...it's an increidbly simple thing. Here's a picture:

Torque arm and Tranny Mount

If you look at that picture you will see the torque arm at the very top of it. It's the black metal piece that you only seee about 2 inches of...as you can see it's pushed up all the way against the tranny housing area. The torque arm will NATURALLY not want to stay down...normally the torque arm is pulled down and then bolted to the black rubber clamp you see on the left side of hte transmission. You can't see it but there is another half to that clamp that would bolt on and hold the torque arm in place there. If the torque arm is not being held in place by that black rubber C-clamp then you have a problem. Also in this picture at the base of the tail of the tranny you will see the black rubber tranny mount...in that picutre if my tranny mount was ripped in half (like my trans am's was) thatn you would see the rubber split in half and know it's no good (like when you try jacking up the tranny it should seperate).

EDIT: BTW that is a picture of and Auto. So yours is going to look a little different if you have a manual. But the clapm holding the torque arm should be the same...tranny mount and the cross member will be a bit different though.