Regarding the rear end, check out my thread. One thing to keep in mind is that the tube are steel and the center housing is iron. They do not weld together very easily. You will need someone who really knows what they are doing to pull this correctly -- there is a very long warm up and cool down process.
I don't have that level of skill or patience, and I ended up tapping and bolting my most recent housing with short grade 10.9 bolts. These were just long enough to go through the housing and tube, but not come in contact with the axle. I used one 12mm bolt on each side, with red lock tight. Works well, and dint require a lot of skill or patience. The housing has to be completely disassembled and cleaned before and after (you'd have to do the same for welding anyway).
I also put moser 7900fm axle ends on my rear diff, which eliminates the c-clips and converts the axle design to a ford style bolt in.