Performance Online’s fuel, gas tanks are designed to fit between the frame rail and rearward of the axle on 1963-72 Chevy, GMC trucks. By moving the tank out of the cab, you gain much needed room to allow for further customization, also increases fuel capacity and safety. Made of heavy gauge aluminum, these tanks offer a light weight design and are fully baffled.Vent bung size is 1/4″NPT. Fuel feed bung size is 3/8″NPT