I was in the same boat when
@ffxcores said lets replace the ujoint. I was like yo it was OK before, his reasoning was that maybe ujoint is so old, can’t handle the new angle. Just so you know I am running 4 degree shims and I was still having drive line vibrations until ujoints replaced.
Ujoint is a much easier job then new shims and new ubolts. I went through 3 set of ubolts just to change shims.
Now I recall even nisstec suggested ujoint when ı was ordering their shims, ı was like nah I need bigger shims haha