i did a homeade shackle flip and havent been able to get it to smooth out. i tried no shims, 2.5 shims and 5 deg. shims. i've also got my transfer case dropped an inch. with the 5 degree shims the driveshaft was 7 degrees at the axle and 12 at the TC. i know i need them within 2-3 degrees to eliminate the vibes, but i also heard that the max these u joints can run is like 13 or so. not sure if that one u joint or both combined. can someone give me some advice or clear up some of my info? i've done lots of searching and cant find the right info. I've since re flipped the shackle to get my vibes under control, so ive got major ass sag. i would go a by a CV shaft, but no funds for that mod at this time. sorry for the long post.