I have the full set of manuals for our coach.
The manuals for the individual appliances are somewhat useful.
The coach manual is so generic as to be pretty much useless. The pictures and diagrams do not match the coach in most instances. It does not tell which tv coax is for which antenna, it does not give wiring or plumbing diagrams, it does not tell which tanks are installed, nor does it tell where the tanks are under the floor. It does give a nice overview of the coach without being very specific about anything. There isn't even a decent description of the switches on the dashboard!
The Ford manuals are like most other vehicle Owner Manuals. They give some information, but considering the modifications that Fleetwood made to the chassis, much of the information doesn't mean much. I guess it is somewhat valuable to know that the "stripped chassis" was not made for ambulance use.
I must agree, go to the manufacturer of the specific appliance and get the manual for the model you have. Go to Ford (or whoever) for the manuals for the chassis. For the coach body, if you do find a manual, you will probably be disappointed.
Keep checking eBay, you never know what will show up there.
Good luck.