I bought one through Amazon for my '80 sedan. Fit like it was made for the car. I also found the filler neck gasket on Amazon, so it's kinda all new back there.
The only issue I ran into was that a previous owner welded the filler neck into the tank. I ended up cutting it off and clamping on a foot long piece of 2-1/4 exhaust pipe. It's nice not to smell gas all the time.....and to not constantly be parked in a puddle of gas! I bought the car in October and have probably spent more than the purchase price of the new tank on patching holes and leaked gas.
Tim D.