Q. about 77' Cobra II

My friend has a 77' Mustang Cobra II automatic V8, he bought it about 3 years ago. He gets a vibration around 60+ mph, he changed the rearend with another Cobra II he had out back he also changed the axels, wheels, and had the driveshaft balanced but nothing helped. I was wondering if anyone knows about a reoccuring problem with these cars, and if they know how to fix it. Thanx.

Anybody who knows anything about this please help! I'm tired of hearing him complain about his car!:o :confused:

I had a 77 II, but did not have a problem with the driveline, except for the fact the damn would never start:p

Your friend has done all that I can think of. I have seen guys get there driveshaft balanced and it still be out of balance, but that probaly not the case here.