Thanks for your comments guys!
David its possible I could use the Caddy IFS, but I'm going for a serious tow rig that could pull a 10,000 pound trailer. The Cadillac might be up to that, but I like the idea of a full-float rear axle and 8-lug disk brakes.
Evan I went through your album hoping to find more pictures showing detail of how you put that truck on a Cadillac frame. I didn't find any and given that you did it 30 years ago I suspect you don't have them. Can you describe how you approached it? Did you modify the frame to fit it under the truck? What year frame did you use?