We used to have a D-35, and it did have an oil
filter, and actually proved to be pretty reliable. Spares and service is a whole different issue. You may be amused to know a whole bunch of those engines were bulldozed into landfill somewhere on the east coast
of the US. Very sad, to me.
That filter was a PIA to change, for it always challenged one on how to not drip all over the place, so good luck with it, but it DID have one. Ridiculous filter change frequency, too, for marine
usage, since on containers to run refrigeration
it was not, absolutely not, every 100 hrs.
Good luck, mate,