Re: Switching to a below deck fuel tank.
That kinda depends on how it will be installed. You will need a thru-hull vent, some vent hose, a brass hose barb for the vent on the tank. A brass hose barb (3/8" ID) for the fuel line, fuel line and some clamps. You will also need some way to hold the tank in place, and some wire for the fuel gauge connections. Metal tanks also need to be grounded to the motor.