Yes. I have a 55 1st design 261 (high mount coolant pump) that is not set up for filter, no provision for one.
All later 261 have the ports, the determining factor is if the pin (above the pipe plug the green arrow is pointed to in last pic) is driven in it blocks the galley passage in the block so oil must come out of the hole that plug is in, out to filter & back to block via port with yellow arrow in 2nd pic.
If the pin was driven in no oil would get to galley without external connection between these 2 ports.
