Lower Unit Application What will it fit?

[Confuzed]

I acquired this lower unit and have no idea what it fits, I was told it would fit my 75hp Merc
but it is not even close in size. The numbers on the case is 1643-6458 Can anyone help me
with what this will fit or direct me to a site that might?
Thanks

 

[Faztbullet]

Re: Lower Unit Application What will it fit?

Thats the small unit housing for the 2 and 3 cylinder inlines (40/50/60/70hp). If you have a 4 cylinder 75hp a 75/80/85hp 2.3:1 ratio will work. If you have the 3 cylinder 75 it take the "metric" lower unit and you have to what years as the had a 3 & 6 jaw clutch dog and will not interchange without modification.