Well, Ned covered some of the points. And thanks, I have been watching that forum as well.
@Rob: Finding a loan on a gas rig over ten years old is difficult if not nearly impossible. That jumps to 15 years with a diesel rig. I am not looking for a loan but what it means to sellers is that a significant price drop is in order because it requires a cash sale. The point being the rig is not going to secure the loan. Track values on NADA and you will see what I mean.
Storage conditions ARE the issues in purchasing a diesel rig. I got taught diesels a number of years ago by the diesel instructor at the college where I was teaching woodworking. I learned that the fuel system must be and remain pristine clean at all times. The get-it-on-the-road cost will be to drain and replace all fluids, replace all rubber items including tires (especially out here in the west), flush all tanks and clean appropriately, check EVERYthing electrical, and replace all the filters. This applies to the coach (house), the engine, and the generator. Might get lucky with the batteries, coach and house batteries. With the checklist I have it will take a couple of people around 4 hours to accomplish this. And a very patient seller. When we get done, then we can look at age and wear and tear issues, like upholstery, shades, awnings, windows, cabinetry, etc. And then there are leaks or potential leaks, the condition of the roof, the water and drain systems, and the bathroom (the room that has had the most use!). There are no CarFax reports. There are RV checks but with a much less definitive disclosure. String and careful sighting will play more into determining if the rig has had major repairs.
What I am now researching is the ratio between the allowable load against the weight of the rig. In other words, how many pounds can I load into the thing and or tow. The other reason for the diesel is to be able to tow a decent sized trailer on something other than downhill.
I am looking for a top of the line model, Monaco, Newmar, Beaver, etc. Some had models with a slide-out in those days. A slide-out is on my list. For me, that would make it a more comfortable full-time living arrangement. There were lessor models offered in that time period but with much chintzier materials. There is some price difference but for the difference I am old enough to want to indulge in something nice.
Running gear desired is a 300-350 HP motor, preferably Cummins, a 6 speed automatic Allison tranny, on a Spartan chassis. That will narrow it down some. But this combination has stood the test of time as reported on the various RV forums. Then there is air suspension, rear cameras, electric steps, tow bars, hitches, solar panels, etc. All extra added value if available.
The other thing I am looking at is enrolling in an RV driving school for a couple of days. This won't be like jumping into my Honda!
Also @Rob: I have a list of websites that I track on this issue. If you need them, let me know.