So with the new Hemi or 440 magnum rear springs installed my Pinion angle is 8.6 degrees down (not good but better than the 11 or 12 degrees down that I started with when I had the 1 inch lower PST springs in the car (no wedges just the spring perches that are welded to the rear end). Let's say my GV unit is 3 degrees down so to cancel any driveshaft vibration the pinion angle should be up 3 degrees (or within a degree if not the exact opposite). From what I understand opposite angles of the GV unit and pinion angle will cancel any vibration provided I start with no more than 3 degrees ). I have the rear end out of the car and the spring perches are welded to the rear end housing at the same angle as the pinion. The Dana was from a truck and I can see the axle tubes have been ground on, maybe a truck has a different location for the spring perches? I will stop and talk to a person who rebuilds rear diffs and transmissions before I do anything. As it is right now I could cut the spring perches off the diff, bolt the diff back into the car without new perches welded in place, set the cars ride height, raise the pinion so it is the exact opposite angle of the GV unit (3 degrees up), tack the spring perches in place, remove the rear end and do the final welds on the spring perches. None of this accounts for axle wrap but I'm pretty sure vibration should be eliminated during normal driving. Thanks for the info on your transmission angle.
Hope you have a great day!