None that I'm aware of. Your motor isn't a through hub exhaust and runs a smooth bore propshaft. Modern props have a larger hub and splined propshaft. If you want to use modern props, you'll have to upgrade to a more modern motor. I think they went to the through-hub electric shift units about 1969 and still use that spline arrangement today. And, no, there's no way to bolt a newer lower unit to your motor either. Well, I suppose if you know a machinist and have deep pockets that anything is possible, but there's no easy way to do it....
I'm with Chinewalker, but I was thinking your question might be can I put a thru hub prop on my '66 100 hp motor? The late model motors have removable hub kits. They are square plastic kits that fit together against a thrust washer on the taper of the propshaft. Your motor's propshaft does not have that design. With enough work a hub might be able to be made work, but the hub has to be tightened down against the tapered shaft to work. Your motor is driven by a drive pin. I don't see a practical way of doing that. Not sure it would give you any advantage anyway?
My current prop is stamped 381442. 13 X 14 then the 14 is marked out and 13 stamped next to it. I am looking for one. I do have a mill and lathe available for machining and it would be fun to make my own adapter.
i am confused with the response. is it about making an adapter?
Additional question. regarding the original prop. merc props have a packing between the spline and outer to "give" in the event of a strike. Is the pin on my drive a shear pin or is there something internal on the prop?
Both props have a rubber hub between the inner and outer metal hubs.
The diameter I am speaking of is the diameter of the outer hub of the prop as compared to the gear case bullet. If the prop hub is LARGER than the gear case bullet, you may have issues with turbulence as the prop won't get a clean bite. Also, your motor has an exhaust outlet at the tail end of the AV plate that needs to be taken into account so the prop doesn't hit it...
Thank you for the insight. I was wondering about a rubber inner. Didn't look at gear case or that tail yet. I would have considered the clearance on the tail but not the gear case bullet diameter. will have to dig out the prop I was considering and see if it is even a possibility.
The 1966 100hp has a big gearcase housing so your hub diameter shouldn't be a problem, but that huge water intake could be as the blades of late model props are swept back a good bit. What are you hoping to accomplish with this endeavor? I am afraid the propshaft is not going to,be long enough to get done what you want. Late model props have longer hubs. Just have to do some comparing. The late model props are normally tightened down on the tapered washer with the nut. Your setup doesn't do that at all!