being this is a 1971 model these were most likely called the 'gray market' trucks.
they are hard to get parts for unless you go to a komatsu dealership and even then you will need the complete model number and serial number off the truck and also the engine number stamped on the engine block.

other than that your options are limited
- either pull the fuel pump off the truck and go to a parts house and match it up
- convert it to an electric fuel pump
- convert it to lpg

I've dealt with these trucks in the past and they are never easy to get parts for from any other parts supplier.