i'd keep the degree shims... check to see how much spline engagement you have on the slip yoke at the back of the transfer case, on alot of lifted xj's still running the slip yoke, you don't have a whole lot of spline left engaged, causing the yoke to be able to wobble(vibration). this can also lead to wear on the splines and possibly dropping the front end of the driveshaft(not good). the right way to fix it is a sye & slip shaft, but for a cheap fix, look into a hack & tap, or you can also try a longer front yoke that gives more spline engagement.