1985 Mercury 175 Black Max Lower Unit Identification

[stalon777]

I have a 1985 Mercury 175 Black Max with a 20" shaft... lower unit locked up on me this past weekend. My question is how does a person identify the lower unit gear ratio other than counting splines on the pinion gear? I think mine is a 1.87:1 but now I see that there were two different lower units made for the 175 Black Max. The only numbers I see available are for the case itself: 1647-9147... no "C" like I have seen others note. Serial #: A137000. Any help is greatly appreciated!

 

[faztbullet]

You have a 2L motor and ratio is 2:1 for it. Only the 2.4 200HP in 1985 used the 1:87. Get ya one from SEI.

 

[stalon777]

You have a 2L motor and ratio is 2:1 for it. Only the 2.4 200HP in 1985 used the 1:87. Get ya one from SEI.

Ok thanks! Will this lower unit fit my motor? The seller says the gear ratio is 2:1...

https://www.ebay.com/itm/4034205946...rentrq:05be28f017f0a77d93a0fae0fff1d756|iid:1

 

[faztbullet]

I doubt its a 2:1 unless it was ordered with that ratio. All 2.4 and 2.5L fishing motor comes with a 1:87 ratio. I wouldnt spend $600 on a used unit, just add a couple more tokens and get a new one with 3 year warranty.