Have a question with the angle of my rear differential yoke to the drive shaft and was wondering if anyone can tell me degree of shims to use. I recently added the RE 4.5" lift. Here are a few pictures. Any help is greatly appreciated.
Unless you have a CV drive shaft I would leave that as/is. With a shaft that has on two joints you want the angles of each joint to be as close to equal as possible. This is needed because it helps cancel out the vibration. So basically if your top shaft is at 5 degrees down then your bottom angle should be 5 degrees up of you can attain it.
I have a 4" BDS lift with Curry 3/4" shackles. I have a Tom Woods CV driveshaft and used RE1469 8 degree steel shims. Alignment is within a degree of perfect. Those shims aren't ideal, but after re torquing the U bolts several times everything seems good. New spring perches would be best - especially if you have some horsepower.