Over the winter I swapped the Olds stamped steel trans crossmember for a Chevelle ((brand X) tubular crossmember. It fits much better, and makes transmission/converter swaps much easier with the big exhaust and X pipe. However, I developed a vibration that starts around 60, and gets worse as speeds go up. It’s worse on decel. I assumed the modifications to use the Chevelle crossmember changed driveline angles, I think I have it corrected now with the adjustable upper control arms.

This is a pic of the protractor on a machined pad on the Gear vender. Since the needle is on the right of zero, that means NEGATIVE 2 degrees?

This is the protractor on the driveshaft, near the rear U-Joint. Since the needle is left of zero, that’s positive, correct?

This is the protractor in a machined pad on the differential, near the yoke.

 

Pull the u-joint cups on both sides... Brinelled? Angle is off. Vert and or horz. You need to look at 3 vert angles first. The trans to the shaft, the shaft overall and shaft to pinion angles. Both ends need offset. Check out these visuals...

Check shaft balance and that the ujoints are centered within the end yokes. Don't rule out the tire balance.