Well, the good news continues... It looks like when the rear drive shaft went it caused even more damage than I originally thought.
Turns out that the guts of both cases are totalled as expected, and of course, it needs a new rear drive shaft, but also the tranny is no good internally as well as the rear of the housing (missing teeth on 5th gear which is the gear it was in when it blew). So I am into a tranny rebuild or replacement scenario for sure. Also the rear third member was damaged and it now needs to be rebuilt with a new ring and pinion, bearing, etc. This AllPro cross member and e-brake setup is pretty messed up, so I am probably going to need a new crossmember, and I will need to rig up a parking brake in it if I want to have one - which probably means going back to the factory setup. So this whole thing has been pretty damn frustrating!
My advice is never, ever, drive a rig with a heavy-walled drive shaft on the hwy at 65mph. Now that I have seen all the damage it can cause if it catches a wobble, I have to say that if you want to run a heavy walled shaft, that means you'd better trailer the thing or else drive like grandma wherever you go. Its just not worth the risk otherwise.