The rear end I used is a 3.73 limited slip rear end, and the axles are five lug, Chevy pattern. I had the work done by a guy who's been doing this a long time, but I can tell you that they used the original springs and welded up triangular mounts for the rear end to sit on. They welded mounting points for the sway bar support struts, and that's about the extent of it. The length of the axle was almost identical to the torque tube, so the tires should sit in the fender wells just fine.
Here's a shot from the rear.
[img]http://www.utdallas.edu/~pauls/trucks/images/rear.jpg[/img]
and here's a closeup of the left side. You can see the sway bar support strut mount and part of the rear end. I don't have a shot of the actual mount that the rear end sits on. I'll have to take that this weekend.
[img]http://www.utdallas.edu/~pauls/trucks/images/left_inside.jpg[/img]
