OK, I saw a recent post about the A-tron shims and I am new to them. Here's my deal: I have a 90 V15 Blazer with 4" lift springs. Front is rough country, rear is pro-comp. Because of the mismatch, it is probably 1-1.5" higher in the front. I saw the a-tron shims and thought that an inch extra in the rear would be desirable, and why not kill 2 birds with one stone and give the drive shaft a better angle. I moved the 1" spacers of the tranny cross member to between the frame and cross member. Because of that the linkage is not ideal any more and it sometimes will pop out of 4WD when I'm wheeling it at Glamis. The $50 question is, what should the shim angle be and can I move the cross member spacers back to where they were originally?