Hey I just picked up a 89 GTA and I am wondering about the transmission. Reverse seems to 'clunk' sometimes when putting it into reverse. And when you shift into overdrive the trans feels 'jumpy' when it goes through the gears. Though the farther it shifts the smoother it gets. And just this morning I started the car up (it was raining out) and the car didn't want to shift into drive. Had to shift it down to first and then it worked fine afterwards.

Now later after letting the car warm up I was able to shift it into gear no problems.

I have checked the trans fluid and it's clean. Also the trans doesn't slip or feel like it has any loss of power when you accelerate. Car has 215k miles on it. But the odd thing is when I checked the bottom of the car the trans was clean! No oil, grease nothing. The cover for the flywheel and torque converter was missing however. As far as I can tell the car is stock with what ever options came with a GTA.

 

Did you check the trans mount? Maybe that's your "jumpy" feel during shifts.