Speaking generically some outboards have a rubber nut that snaps onto the shaft.
If there is no cotterpin it probably snaps on.
You might ask at Johns Old Mercury Web Site.or ask at www.aomci.org
I could be wrong but i think it turns off. It has a star like washer with tabs that fold over the nut keeping it from turning off. I have tried to turn it off but the washer as well as the shaft turn together. Any suggestions?
