Help ID mercury lower unit

[Kzaker]

I picked this lower unit up from a guy closing his shop. He said it was from a 200 Merc but after looking on line for references, I’m beginning to think it may be from a smaller 90-115 HP opti, anyone familiar with these units available to help me figure out what it may be for? Looks to be in great shape so I’d like to have it put to good re-use.. any help is greatly appreciated. I did also post on the 2.5 thread but haven’t had any hits, that also is why I’m thinking it may not fit in the 2.4/2.5l realm.



Regards,
Karl

[EuropeanAM]

Likely from a 75/90/115 (such as on of the 3 cylinder Optimax models).

[Kzaker]

Thank you,
EuropeanAM, what’s the difference between the lowers for the mid Optimax vs the 4Strokes?


Maybe I’ll dissect it as a learning tool.

[Kzaker]

I was just told that this is for a 4 Stroke, the top of the shaft has two sets of splines. Is there anywhere that I can find bolt patters or any other identifying characteristics?

[EuropeanAM]

Case is the same- differences were in the driveshaft (which doesn't show complete in the above pictures), and the gear ratio.

You could check the gear ratio... same rules apply with it off the engine (just substitute driveshaft for flywheel).

Determining your Gearcase "Gear Ratio"- Without removing Gearcase