why do you want change the oil pump? low pressure? There is a valve on the engine that you might want to inspect 1st. Its a spring loaded check valve that helps create oil pressure.

The F163 is a later model of the F162. Externally you can tell the difference by looking at the fuel pump or the fuel pump block cover. The F163 has the 2 bolts for the F P horizontal, the F162 has the bolts diagonal, your truck is probably a 163.

Those engines are great, they help win WW2, put in many vehicles, very reliable