I have a 96 Sunfire 2.2 engine with a 3T40 automatic transmission (190k). The whole story is this: Last night I was reving the engine from the throttle body so I could listen for a bad bearing in the belt drive. The transmission made a loud thud (in park) at about 3k rpm. it only happened one time and everything was fine after that. This morning it would not back up. it reved up and caught jerking backwards. it was fine for the 34 mile ride to work but now it will not move (hot or cold). and if I put in neutral it will ratchet forward but locks up if I try to push it backwards. PS: It is 8000 miles after a new transmission filter and topped off with dex6... Any help or ideas would be great. Thanks for your time -Rich

Almost exactly what the transmission on my 97 was doing when it went at 120,000 miles. Sorry to tell you that you'll probably need a new one put in. I think the dealer charged $2700 for a reman and labor.