Check out Sands RV on rt 20 if you haven't already. (Madison) They have ton of surplus stuff, good prices. The owner's dad was the builder of the Ungers Motorhome. They also used to sell FMC and Revcons. If you tell him a Revcon owner sent you, he may even remember who that is. You will probably not find specific OEM stuff for it, but are likely to find stuff that can be used.
As far as lights, I would (and have) converted to all LED. The wiring in your coach is old and tired. It will be much happier with the light load of LED lights.