Greg, since I think this is going on your 4x4 build project, since you are using an 05 Superduty frame, take a look for an Excursion (which was available with a diesel engine) fuel tank. The 99+ Superduty pickups used a s ingle, midship mount tank on the drivers side inside the frame rail in front of the rear axle. The Excursion used a single, 44 gallon aft mount fuel tank. It mounts in the "frame box" between the trailer hitch, and the rear axle, between the frame lrails. The filler on these is similar to the factory rear tank filler, straight in from the side of the body, behind the drivers side rear wheel. One nice thing about this setup is with the factory Excursion venting and fill tube (which has no "door" like a gasser filler) my preferred fuel stop has 1 pump with a normal auto gas sized nozzle, and one more for medium duty truck sized nozzle. I use the larger nozzle which just fits inside the fill tube, I can open that nozzle wide open and fill as fast as that pump will fill. (about 30 dollars in about a minute or a minute and a half. These tanks are "plastic" with a skid plate style mount. One thing though, like the Bronco tank, you will loose the ability to store the spare tire under the truck if you so choose. The Excursion spare tire is stored inside the passenger cabin, much like station wagon. I will say it is a big honking tank.... and I do not fill it full very ofter anymore..... it takes some coin to fill it at current fuel prices......