Agreed that the tank life will not be the same as a new tank. I'll continue researching tank replacement options. This coach did a lot of sitting before I bought it. Since purchasing I have purged the tanks often, but not every day.
My coach does not have a drier, and as best as I can tell it never had one. Installing a drier has been on the list of to-do items since discovering that one was not on the coach, but I have been addressing other items first. However, if I'm going back with a new tank I'd like to install it with a drier at the same time.
One of the things stopping a drier installation are some open questions that I need to get answered. Does anyone have a recommendation on a drier model and where to install it? When driers were installed, which drier was used and where was it installed so that the desiccant/filter was accessible? One spot is in the engine maintenance bay because it is where the fuel filters and other items live, but there may not be room since it's already a pretty busy place. Another possibility is the rear access door but there's not a lot of clearance. The battery bay is right next to the engine bay and close to the air tank, so I suppose that's an option if space permits. But there are a number of reasons not to put it there too. In any case, I'm open for input if anyone has an opinion :-)
Thanks again for everyone's help!