Cat 20 Oil Filter

I am rebuilding a Cat 20. The engine has an oil filter on the block on the right side back of the outside. Looks like there are two filters and they are about 7 inches long. I need to know the part number. Can anyone help me.

The early oil filter on the Twentys used a stack of felt washers that was held together by four wires and two washers which was put on a special bolt and compressed with a spring. The felts and filter assembly have been discontinued for many years. I was going to try a paper type filter as a replacement and if I remember I found one that fit nicely but I can not remember the part number right now. I will have to look in my notes when I get home and see if I wrote it down. I never tried the paper filter because I have never put a Twenty back together yet, still gathering parts for the one that I want to put together.
Thanks
Ken