D6c question

Hello everyone. I have a quick question. I just purchased a old d6c dozer. From what I can tell it’s around a 70s model. It has the none turbo motor in it. I need to change a fuel filter and there is no numbers left on it. Just wondering if anyone would know the part number for one? I have a manual that comes with the machine “as soon as the guy can find it” lol. I tried to find a vin number on the machine and can not find one so hopefully someone can help me out.

Thanks
Randy

D6c question