Good luck on finding manuals and wiring/plumbing diagrams. Often the manuals are so generic so they don't have to be re-written for every model or accessory they aren't much use. I suggest you crawl over, under, and through every space and write down make and model, fuse, and valve, you find. Then Google manuals for each component you saw. Thor shows Four Winds owner's manuals for
1996 then it skips some years.
https://thormotorcoach.com/document-archive/?cat_id=14
The Ford 460 (7.5L) didn't have exhaust gaskets, a leak usually indicates a cracked manifold.