My 93 had the older 4 wire controller, it did not work and was bypassed by the PO. I just recently rewired it to use the newer 3 wire controller and installed a time delay relay, also added a push button in the cab so I can override it if I ever need to.
never trust what the auto parts house says a vehicle is suppose to have. especially for a RV. a good while back I did brakes on my 95 truck all the way around. I bought new wheel cylinders for it and they told me I needed the smaller ones since it wasn't dual rear wheels. after installing them and having issues with the brakes, I took a trip to the chevy dealer and gave them the vin. they told me the auto parts was wrong and I needed the larger heavy duty wheel cylinders. After swapping in the larger ones the brakes were much better!
What will is trying to tell you is make you a book to keep with the RV and note all parts you can in that book. get as much info as you can on it from when it was built from the factory. this way when you break down and need something from the auto parts store, you know exactly what to ask for. you will find things on your RV that is the same as one vehicle or another. usually multiple, an example would be when needing brake parts you might have to use the application for a given year 3500HD truck and for engine parts you might have to use an older application non-HD. If you can get in touch with the dealer where it was built, getting a full detailed build sheet is as good as gold.