Most RDS transfer tanks also provide auxiliary fueling. RDS offers a full assortment of tanks in various capacities and dimensions to fit your needs. Auxiliary tanks connect to your vehicle's fuel tank. Diesel fuel can “gravity feed” from the bottom of your RDS tank. An optional Diesel Install Kit contains the necessary items to economically and easily connect your RDS tank to your OEM fuel tank. Gasoline auxiliary fueling is allowed, if siphoned from the top of the tank by using an electric fuel pump.