Sounds to me like your local parts guy is either to dumb or to lazy to look. Has the oil filter been converted to the full flow cartridge type? If so the current Cat number is a 1R 0659 or go for the Napa/Wix equivalent a # 51161. The Napa/Wix number for the fuel filters is a #33164.
On the no fuel pressure after checking the obvious candidates for pluggage, check the fuel transfer pressure relief (on inlet). They are notorious for deteriorated spring, worn valve/valve seat, or just plain filled with crud.
Just take him the part number and tell him you need 4 fuel filters and 1 oil filter. He'll probably have them in stock.
It's 4 fuel for the 5U D2's, I'm guessing it was the same for the earlier.
D2 5J used three fuel filters. 3J should be the same. Otherwise do everything these guys said. It works for me.😉
Jack
My local NANPA had the filters for me. 3 in the fuel on the J models. One oil filter. The part numbers listed by others look correct.
drujinin in Elkhorn WI
My luck with using aftermarket fuel filters is that I still had to go to the local Cat dealer for the gaskets...the J's filterhead gaskets are different than what was sent.