Aftermarket gas tank?

Curiosity, does anyone make a gas tank for a 69 Dart that carries extra room for gas? What I mean is if I cut out the spare tire area and make the trunk floor flat.

Thanks
you can get a custom tank built to you specs for a decent price or look at some of the fuel cells that are out there. In my dart build, i cut the spare tire pan out, measured and found i can get a low profile, 25 gallon fuel cell rated for SCCA use from summit for about 200 bucks, with sending unit. Only thing I gotta figure out yet is how im connecting the filler tube.