I think I may have found my vibration.I talked to a guy at Strange Eng. and was was talking about critical speed and jump-rope.Don't know if ya'll ever heard of that before.Anyway,with my small 2.5" dia. d-shaft (52.5" long)and the rpms(6600 on the tach thru the lights) I'm turning he seemed to believe that it was causing my d-shaft to "jump-rope".I believe he may be right.The factory frame on my car has a real small tunnel that the d-shaft runs thru,that combined my the off set on my pinion(to the pass. side)puts my d-shaft about 3/8" from my frame tunnel.Well...I know that's pretty close but it has never hit before,plus there shouldn't be ANY side to side movement with a ladder bar and diagonal link setup.I know a panhard rod has side to side movement,but I don't see how a diagonal link cause have any,or very very little.Any who,I have a witness mark on my d-shaft pipe and the edge of the tunnel where it has hit! :shock: BUT,the mark doesn't go the full circumference of the pipe,it's just a scuff about 2-2.5" long.If it was hitting and riding it,it would be all the way around the pipe,right?Maybe she is playing jump-rope on my after all.And my vibration is feeling the pipe jump over,smack the frame and coming bak and forth.Oh well.that's the best I can come up with for now.Anyone got an opinion on this?I'm wide open to suggestions.