Yamaha m-21 propeller on mercury 150 efi

[Apex2007]

I’m trying to figure out what thrust washer to use when mounting this Yamaha prop on my mercury. The prop has a fixed hub with the inner portion recessed about 1/4 inch, it is not flat. Should I look for a mercury thrust washer or a Yamaha one. I’ve heard that the prop shafts have different tapers. I have used a mercury flat trust washer thus far but it does not go inside the prop, which I think it should. The boat is a charger dl18, with tank in the back so this prop works great because it has very little lift which is great, don’t need it. Tried a tempest plus and had to run with trim down all the time at cruising speeds, not so with this prop. It is a yamaha painted stainless steel.