Hey, Farmboy! Welcome!
You are doomed, of course. It's got you.
LMC Truck is a good place for parts. Remember though, it's just an 84 Chevy truck. Except for a few military doo-dads, it's pretty much a 1984 K30. Parts is parts. Junkyards are your friends.
I don't know what year you have, but it doesn't matter much. For parts, you have an 84. The Army didn't want the hassle of dealing with model year changes in their supply chain, so they required them all to be built to 84 specs. When you need parts, you want 1984 parts, no matter if your truck was built in 84, 85, or 86.
I have no clue on the transfer case, but I'm sure some of the experts here will comment.
Just some general advice to get you going: If it's rubber, replace it. If it's electrical, clean it.
Check out the Helpful Threads sticky - top of the CUCV forum. It's full of excellent info. You also want to download the TMs (Technical Manuals. Freebies! Very useful. These are the three main ones:
TM9-2320-289-10 - Operators manual for all variants of the CUCV.
TM9-2320-289-20 - Unit maintenance manual for all variants CUCV.
TM9-2320-289-34 - Intermediate support and Direct Support for all variants CUCV.
You'll see these talked about as the "dash ten", the "dash twenty", and the "dash 34".
There are also "dash P" versions, which are the PARTS catalogs to go with each of the TMs. You can look up parts diagrams and the GM part number for each part.
There are a ton more. You'll want to look them over.