What year is this dually

[55belairtim]

41,42 trucks used a rubber seal around the gas tank filler neck the later trucks 43-46 used a leather seal to save the rubber for the war effert, im pretty sure that a 41 has a trunsignal lite thats different from a 42-46 truck. the best way to deturmnin is getting the vin off the engine if its original. i rember reading somewher that if the vin is missing on the cab the only other place it was located was the engine block
thaks tim