cant find a prop nut

[Soundtrackzz]

Hey peoples. I have an old Mariner 5C outboard from 1983. The prop and prop nut spun off so i need new ones. I can find the prop but i cant for the life of me find the prop nut. They dont make it anymore and no one knows what to replace it with. Its a cone shaped nut that no ones seen before. Heres a parts diagram that shows what im talking about, 5C Mariner Outboard 6E3-102151 AND UP GEARHOUSING ASSEMBLY Diagram and Parts (its number 54). Does any one know where i can find that part, or what i could substitute for it? Buying a whole new engine because i cant find one part seems pretty ridiculous.

Thanks
Z

[S/V Antares]

Same as a Yamaha, They made the mariners and mercs under 10 hp
1984 5LN Yamaha Outboard LOWER-DRIVE Diagram and Parts