Yea,that sounds like a tough one.Like 1stn2nd gen. was thinking,if it is engine,or tranny related,RPM would have an effect on it.A friend of mine had a truck once with a mystery vibration,it turned out to be his main bearings in his engine.What happens if you get it up to vibrating speed then shift into neutral?If it goes away it's probably engine related.And this test is free!I don't know how you can accurately test to see if it is tranny related,except to swap trannies?Of coarse a last resort.Maybe pull the inspection cover off of the trans. to look for converter or flywheel damage.I don't know how much $ to balance a driveshaft,maybe cheaper to get one from a junkyard just to swap it in and see if the vibration changes?Also this is assumeing that all the work you already had done was done correctly and used good parts i.e. putting on a used bent rim? Just random thoughts,good luck.
67 RS RAGTOP # matching, 4X4 CHEVY TRUCK
[This message has been edited by 67drake (edited 01-09-2000).]