You are going to be hard pressed (near impossible) to find a custom fit tank for that 1 ton. If you're dead set on getting one back there, you are going to have to take measurements on the frame rails and find a fitted universal tank that will fit. In my opinion, just use the original behind the tank. If you have new hoses and a solid tank, the dreaded fumes don't exist. I have my tank behind the seat and I can't smell fuel.
