I have a 77 camaro that I have been working on and I now feel that the rearend needs rebuilding, when driving the car if you get on and off the gas I feel what seems to be the yoke and pinion moving in and out,there is very little noise coming from the rearend, but I have noticed that at high speed over 80mph there is a bad vibration until you get off the pedal and on the way back down from 80mph it's really sakes hard until under 80.I planed on having the rearend rebuilt but I just wanted to know if this sounds like a rearend issue,don't want to spend $600.00 and thats not the problem.I have had all tires and wheels checked and double checked, because I just don't want to do this rebuild and this is not it. The unit is a 8.5 ten bolt with a trac lock unit,342 gears.I will be going to 373 gears, and the car is a auto,Will the gear change make much difference and do you all think that it may be the rearend? I do get on the car pretty hard sometimes but not a habit. need some help please.