That is some freaked together stuff. I'm gonna disagree with jopes and say it's a Dana 21 (single range) or 24 (dual range) transfer case.
The front, looks like an early 70's with the disc brakes off a mid-70's. Whomever welded the steering ear on the passenger knuckle should be slapped.
Bronco or f-series front driveline, too much crap on there to see how they attached it to the t-case yoke, but I'd guess u-bolts and some goofy sort of adapter.
Interesting radius arm brackets, I don't recognize them but they look like beefy castings.
All in all I'd say it a pile of crap.
Thanks for the input everyone. I was trying to figure out what this 4x4 set up is on this E300 van that I was thinking about buying for fun. The interior and upholstery is in good shape, swapped to a nice 351 with flowmaster exhaust, straight body but seems like goofy 4x4. The guy wants $1500obo for it, so what do you think?