2. This is the early-’69, unvented, 20-gallon tank (PN 43314) for the 390-horse 427 with Rochester carburetion. These tanks are exact reproductions made from thick, 0.032-inch Ni-Terne steel and pressure tested. If you’re performing this job with the body installed, simply roll the tank on its side, and it should fit through the area between the crossmembers. The beauty of the body-off approach is that it allows you to see exactly how the tank fits the chassis.