Just in case you're PO'd at Ford on spare parts for the GT they aren't the only one. A couple of years ago the Dodge Dealer broke the fuel tank on my truck while replacing a fuel pump. It's the oversized 33 gallon tank. None are available from Dodge (even today) and there is no aftermarket tank made. He and I separately scoured our collective "junk yards" until he located one for which he paid.
The reason for the concern is that the tank didn't leak gas, the break was one of the evap lines to the top of the tank so the failure was an emissions "slow leak" check engine light. This gets hairy. I can't pass emissions in Nevada with a Check Engine light or an emissions pending code. I asked the dealer what would happen if they can't find one since no emissions pass is essentially scrap the truck. It never got that far and I never got an answer from the state as to what to do if you get an emissions related fault but the part is no longer available from anywhere...