imagine 2 kidneys-1 behind the driver, the other behind the passenger. there's a connection over the driveshaft where the fuel transfers by way of a suction pump from the lh side, return from the engine, to the rh side, where the filler and main fuel pump is. there are 2 sending units and the gauge on the dash averages them. 1 way to drain the tank is to pull both senders, but it's tricky unless you have the special tool or and adjustable pin wrench with the right diameter pins. good luck, chuck.