Also don't forget that the B class of that vintage was also sold by other manufacturers that may also use the very same tank, so don't just limit your search to Airstream.
Coachman, Okanagan, Chinook built them, just to name a couple, with a quick Google search you should come across a whole bunch, and then if you go into their layout you should come across a few that have the same, or almost the same interior layout as your own, so the tanks maybe the same; go from there. At least you won't have to pay an "Airstream" price.
Per Mare, Per Terram and may all your campaigns be successful.
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