The propane tank on my '88 Westfalia is leaking.  Soap bubble test
confirms that it's not the valve, fittings, lines, etc. - it's the tank
itself.

At about the bottom center of the tank, there's a thick plate about three
inches square welded to the tank.  The tank and plate are covered
with rust.  The leak is right at the edge of that plate.  Does anyone
know if this plate is a "normal" part of the tank, or could it be a
patch that a previous owner applied to an earlier leak?

I assume leaky tanks are thrown away, rather than repaired.  Is that
correct?

Anyone know an inexpensive source for tanks?