It seems like there would be proof in the form of a photo.
Or service manual drawing.
I just googled about a dozen more photos and none had anything attached there.
Small outboards don't normally have "options" that would require additional mounting bosses. That stuff just adds weight.
The only engine that mounted any thing there was the 1964, the first year of the 9.5.
So perhaps the OP has an Engine, or at least an Exhaust Cover that is older than 1971
I finally found a filter for a 64 that looks like it would fit the cavity at the end of that mounting boss. Still haven't seen any photos with the filter still in place. Maybe it exists only in museums now...
But all year 9.5s still have that mount, from what I've seen.
What have you circled there?
I've been curious if that square socket in the casting has any purpose.
I've used it to crudely try to keep the flywheel from rotating when torqueing the top nut--but it feels risky.
