My wife just got me a Dana (think it's an S130) rearend for my '52 9700 GMC.
2003 ford F450. Simply unbolt hangers from the ford frame, it's the same width frame as the GMC. Mines not in yet, but looks to be a very simple swap, I'll end up with 4.88 gears, limited slip, and 19.5 rims with Radials. Just have to drill off my factory hangers off the frame, roll this under and bolt it up.
So, an easy option to go to (or, I also have possibly the same rear as you, that I'm not using) mine is an Eaton 2 speed.
