I have a world class 5 speed with about 9000 miles on the rebuild. Just recently when I shift to 5th gear the car shakes really bad any ideas as to what is causing this??

 

What speed are you at in 5th gear? Possible causes include out of balance tires, driveshaft, flywheel, or clutch. You could also have a problem with your u-joints or the rear end.

 

I have tried shifting it into 5th at several different speeds and it does it at varying speeds high, med, and low. I have an aluminum drive shaft and 3:27 rear. I'm begining to think it might be my rear end or 5th gear going on it?? I even feel it doing it in 4th gear at lower speeds around 35 miles but not nearly as pronounced as 5th and it goes away as I accelerate. Never did this in the past just came out of nowhere.