If you can find the above manuals etc, they may help, at least take you back to the Dodge chassis BEFORE the RV portion was added. It can be hard enough to get manuals for 5 year old RV, 50 years!!.
You would be best to look for and OLD school mechanic, one who uses his hands, she's and knowledge to diagnose problems, not a new school auto technician (No offense intended) who plugs into a computer to see what's wrong.
If you have an automotive restoration place in your area, maybe they can point you in the right direction.
Ken