The difference between B and C variants were new self-sealing fuel tanks. Because of their structure the capacity of these decreased to 135 galons. In order to raise the range of P-40 the fuel drop tank of 52 galons was added. Instead of that there could be the B-7 bomb rack mounted for a 500lb bomb. And it was the only thing that could be seen as the difference in the outer view between these two sub-types.