My IROC has a vibration that starts about 45mph. It's pretty violent by 65mph. I replaced the axles, thinking they were bent, but no. I rebuilt the rear while it was apart. My question is, on jack stands, the driver's side rear would bounce up and down. Would a out of balance drive shaft transmit the vibration to just the one wheel? I think it would because it's an open differential, and that's the wheel that was turning. Oh yeah, tires have been balanced, and the wheels are true, so that's not it. The U joint is tight and has no give. Ideas? How much to balance a drive shaft, and do you have to take off the torque arm to get the shaft out? Would it be better/cheaper to try to find a balanced aluminum shaft? Thanks, Scott

Yea, the drive shaft could be the culprit. I had a very bad vibration in my 82 and it turned out to be the drive shaft. The company that made me a new one said the General uses junk tubes for their drive shafts. He showed me the size of the weights on my old one and what the new shaft had on it. It was amazing, the car is smooth all the way through top end..
Take your shaft out and have a reputable drive line specialist look at it put it on their mach. to check its bal..
Good Luck..
cc82Z-28

Thanks for the response

Does the torque arm need to be removed to take out the driveshaft?

no

No, it does not. It's just a little close under there, but you can pull it out. Also mark the yoke at the rearend so as to put the drive shaft back in the same position it came out, or as it is called backe in phase I believe.
cc82-Z28