I have had this car for about two months and it started doing this right after I got it. When I am taking off from a stop, and the tranny hits 2nd gear it hits real hard in the rear end. I don't think its the u-joints cause there is no slop in the drive shaft, plus it doesn't do it all the time and it only does it when the tranny hits 2nd gear from a complete stop. The tranny has no overdrive, I believe its the 4spd automatic trans, they put in that year. The car doesnt jolt at all when it happens its just a real load thud coming from the rearend. Any suggestions out there, oh I did reaplace the tranny fuild and filter about 100 miles ago, but it still does it. Thanks