Big end almost always goes toward the rear. This should correct a bad pinion angle (you want the front of the rear to be angled down a little). I'm actually going to taper the blocks on my s-10 to correct a bad angle.
4x4 angle up (taller in front) lowrider angle down or flat. pinion needs to be opposite of trans angle.
Ive never messed with em, only flat, but yeah supposed to correct a certain amount of pinion angle problem.
thanks guys i got er figured, i used 4 inch 4x4 blocks and put the big side to the back and it seemed to work.