Yamaha 40HP Stroke 3 cylinder mid 80s - Prop

[markpoint]

Evening, I have a Yamaha 40hp 2stroke 3 cylinder mid 80s outboard. Does anyone know what prop this OB should have, the one on there looks too small. I have been told the Yams and Mariners of that era are the same engine, I believe they're 13 spline - anyone know for sure ? Thanks

 

[Boathook]

I used to have a Yamaha 30hp 3 cylinder from early 90's. The splines are the same as the honda 30hp, though different length. Not to sure whether this is of help. With regard to prop size it would possibly be the same as present engines or possibly the next pitch down to allow for slightly less torque.