Work from the past couple nights....
Got the new (used) rear x-member in and done. It's a used one off of the original tub from the truck. This is a different tub that I'm using and it's had some work done to the back including replacing part of this x-member once. It had been sectioned with a couple extra brackets holding things together, and not very well. This x-member isn't perfect but it's not bad and still better than trying to reproduce it from scratch.
From there I drilled out and removed the old end-panels, cleaned everything up and test-fitted them. They're aftermarket panels but they fit pretty well. Drilled everything, applied a good coat of 3M panel bonding adhesive, set 'em on and riveted everything tight. I would have rather not used rivets on the outside surfaces, and probably didn't really have to, but I'd rather the body strong than pretty. From here I'll fix the few dents in the sides and prime them up, prep and paint the floor before installing the steel floor supports and then I'll paint the inside. It'll go on the truck before the outside is painted so I can install the dog-legs and paint them along with the rest of the tub sides.
Anyway, a picture is worth 1000 words.