This article will tell you how to set pinion angle:
http://www.carcraft.com/howto/91758/
Or this one for 4x4:
http://jniolon.clubfte.com/driveline...nephasing.html
I have broken 6 12 bolts in the Jimmy, including one trying to remove a stump. I really want to upgrade to 8 lug wheels, not because I need them, but just because. However, wheels and tires in addition to a front 8 lug setup will eat me up. So, in the meantime, if I break the 12 bolt again (or should I say when?) I am planning on installing a semi-floater 14 bolt with the 9.5" ring gear from a late 80's-early 90's light 3/4 ton truck. That should be significantly stronger for not much money and I can retain my current 15x10 inch rims. Most semi-flaoters were 4.10 geared in 3/4 tons, but Z71 1/2 tons will have 3.42 or 3.73. I have 4.10, so that works well for me.