Joe, the original cotter pin hole is drilled at an angle from inside
the threaded bore, and comes out in the hole about an inch up
the leg. Someone decided to drill a cross hole through the gearcase,
for the cotter key, perhaps to make it easier to install?
Buck, I suspect someone lost the pin
your motor had a pin originally. You could
probably make one and braze up the holes.
You are getting pretty good with that stuff.
Tubs.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.