To all:

Thanks for all the replys to my question. It does seem like try a switch would be A) too much work and B) might not be the best tranny to switch to. I have been driving around under 55 in drive and only using the overdrive for the freeway. I like the idea posted about a bullet proof rebuild...but that would have to wait for funds. I'll also check the joints on the drive train...it does make sense that, if there was a little play in the joint, during a shift it would compound the thump that I hear and feel. Two other ideas occured to me, is it possible to lock out the down shift at high speeds so that if you were going 75 and came to a hill while on cruise control it would not automatically try to wreck your tranny? And also, has there been any success with automatic to manual conversions...if so is it a difficult switch, is it a smart switch, and which transmissions are recomended? Thanks a lot for the previous responses to my question...cleared up a lot of questions.