so im getting my leaf springs replaced tomorrow long story short got my leafs in nov put em on in late may early june with it being winter in mass then tons of rain and all 4 bushings are already shot to ****, anyways i can grab a set of 4degree shims and have them put on with the leafs tomorrow should i do this for my driveline angles? already have an aye and tom woods rear shaft.. lift is at 5.6" long arm and i get slight vibs at 60+ and they increase faster i go past that. top out round 70-75mph.

 

Might as well

 

I use 4* for 4.5. Every jeep is different but ill bet you need more.