I have every thing from a 1979 G-30 One Ton Pathfinder van that I parted out.
I was going to install it in another van but I just sold the van tonight and the guy want to restore it to stock condition not 4x4. The parts will fit any 1971-1982 GM van 10-20-30... They also will fit 1983-1995 but the front frame rails changed so they would have to be fabricated to work..
Dana 44 Front 4.10 gears
GM Rear Axle with a Gov Lock
NP 205 Transfer case and Turbo 350 Adapter
Front Frame Insert with Spring Mounts (drilled out and ready to install)
4 Leaf Springs( could stand bushings or to be rebuilt to be perfect)
Engine Cross Member
Drive shafts and a Bunch of little parts.
Shipping might be a bunch but you can have it all for $800 plus any information I have
Blueprints, Measurements, Pictures and such. I did one of these before this way and it worked well.
The Boulder stuff is nice from what I have seen.
You can also check with Gordon at Pathfinder. He sells parts for Pathfinder vans and there are many links on his page so look around and you can find out more about converting an older GM van, here are a few.
http://www.pathfinder-vans.com/
http://www.pathfinder-vans.com/html/gm_kit_info.html
http://www.pathfinder-vans.com/html/dave_engels_editorial.html