I got mine from
Here. This is the only place I found a tank I needed. I wanted it to be below the rails of the truck so I could close my Tonneau cover and I wanted about 45 gallons of fuel.
I brought to a shop to be installed. Mine is gravity fed. I have a shutoff valve on the tank. It drains directly into the tank. no need for a pump.
I purchased this because I hated going to gas stations with the %th wheel. most places are tight to get into. I don't like using truck stop pumps either. To much trouble going in leaving my credit card, pumping, going back in and paying. Now I only need to fill in the evening when we get to our destination.