Dave -
Congrats on the '71 Safari. Our '72 Overlander's black tank gave up
the ghost early this summer. Concensus was that it wasn't worth
trying to repair 30 year old plastic. I had visions of big bucks for
a custom tank, but it turned out that Airstream had one in stock!
Still big bucks, but available rapidly, and it fit. Might be an
option worth exploring - I just called Parts at the factory, and got
the (to me) surprising news.
Stan