is there a rule of thumb that says RVs shouldn’t be older than
As said, very good inspection then weigh to cost difference of repair over a newer unit. Personally I would prefer a newer 6 speed tranny over a 4 speed.
It also will depend on where it was stored. If it was in a dry climate that's a good thing. If it sat next to a boat ramp or was on an oceanfront lot of a beach club then I would pass on it.
You would probably also pass on it too when you attempted to move it and the wheels feel off. Regarding the chassis I think rust and corrosion will be the enemy to inspect.
Regarding the coach, it will be the caulking and how it was maintained over its life. Water intrusion will seeks the lowest level to settle and follow gravity using the framework as roadways. If you have water damage in the drivers side rear, the leak might have originated on the passenger front side. Floors and such should feel solid not spongy, check the floor at the entrance door. Rv doors are notorious leakers.
