What fuel cell fits nicely in the spare tire well 70 Dart?

The one I have measures 20" wide x 15" deep x 8" high. From the top of the cell down to where the 2 pick ups are it's 10" high by 6" wide. I took some pics of but I left the camera at the shop tonight..I want to say thats it's a 10 gallon cell,don't know what brand,but I did buy it at Tognotti's Auto World in Sac.