buying an '82 26 fooe class c needsome info

needs a bit of work, dealer is a friend and paying for the repairs, however i need some info, its a f350 chassie i cant seem to find the inverter, and the fill for the propane tank, there a locked 'hatch on the rear driver side corner but we don't have a key, I also need a wiring diagram, how big is the propane tank, motor home had dual fuel tanks, if any one have any info, i would appreciate it. jsharpe45@yahoo.com

I own a n 89 E350 EMC. The propone tanks and filler are immediately behind the drivers door behind a sometimes keyed or unkeyed entry. (on the outside of the motorhome) Be sure they are off when traveleing.