I've been looking for years for info on fixing up old mobile homes, (I'm stuck with a 30 year old one!)
The only source I know of so far is an insurance company, believe it or not! They specialize in insuring them and also have, own or operate a parts center for some of the hard to find replacement parts.
Try this address and or 800 number. It;s for the insurance part of the business, but they should be able to supply you further info on getting their mobile home parts catalog: Formost Signature Insurance Co. 5800 Formost Drive S.E. PO Box 2450 Grand Rapids Mich 49501-2450 1-800-527-3905
This may give you a start. If anyone else has info, give a holler 'cause I'm still looking too!