Re: 13 splines prop
To some degree.
The things that can be different are # of splines, shaft diameter, shaft length, prop diameter and pitch.
Within a given manufacturer this can change over the years for the same hp too. Conversely, they will use the same lower unit on a "family" of motors making the parts interchangeable.
Dunno what you have in mind, but my best advice to you would be to purchase a propeller intended for your motor. It could very well be that a Mercury prop might fit on your Yammie, but at least check first.
What year is your motor and what type of boat is it on?
The crew will start pulling good suggestions out the wazoo with part numbers for you.