Phil,
Now that I know that you are dealing with an older coach, let me share something with you. I hope you have been warned about the roof already, if you have any doubts about its integrity deal with that now and first. RVs with roof leaks end up in big trouble fast.....
Next some relatively easy things. Total cost about 500$ including tools and all materials if you do it and you can.
All the rubber parts are over age. This is a calendar problem. Adhesives and elastomers have a limited life. That is all there is to it. So, plan to at least inspect if not replace all the hoses for fuel, coolant and brakes. While you are doing that it is a good time to flush the cooling system because the corrosion inhibitors are depleted. The brake fluid has probably absorbed some moisture to rust expensive brake parts so flush that system. The rubber fuel lines are old enough to give trouble all on their own, but most likely they are not compatible with current "motorfuels".
You may be asking yourself what does this fool know....
The coach in my signature is a 1973 model and I worked for 40+ years in the testing laboratories of Detroit.
Matt
Matt & Mary Colie
A sailor, his bride and their black dogs (one dear dog is waiting for us at the bridge) going to see some dry places that have Geocaches in a coach made the year we married.
