About the cut and turn of knuckles
I have done a few of the knuckle turns both by the pipe cutter way and now via a lathe (the proper way)!! The best way i could help you, if you're gonna do it in your garage is this way: completely disassemble your diff assembly. Then take a grinder and carefully remove the welds on the ends of the tubes. do this until you have an even surface equal to the tubes diameter. Then you can take the pipe cutter and go round and round and round.
you will go through the outer tube after a little while. then stop and you can put a long bar through the bearing race holes in the end of the tubes and turn your outer ball to your desired caster.
make sure you use the same reference point for both side to determine your caster degrees. This way at least you will have an equal amount of caster to the diff assembly. Then when you've checked a few hundred times check it again, just to be sure, and then do the best penetrating weld you can. (Splash weld). Then you can reassemble your diff.
Any other questions, like what degrees for caster and such, just ask. I have found that about 3-5 degrees is best for highway driving and wheeling and easier on your steering components.
Kruzrtek