Pinion angle and drivetrain vibration

Based on what I've read, I believe you're correct 67Dart273.

I picked up some 2" wide 4* shims today and will be putting them in this weekend. 2" seems narrow, but I suppose as long as they're flat and allow the centering pin to reach the leaf spring mounts on the axle, it should work?

Wish me luck, and thanks again everybody.