Help with lower unit

[Brianhardesty]

Having trouble with the year and what lower unit on a mercury outboard,all I can fin is the serial it’s a183639, I’ve read it needs a 206 b20 and I found a 206 a20 that looks the same but I’m not for sure

 

[Chris1956]

Gee, what about telling us the year and HP? Newer motors can usually get replacement gearcases from SEI.

 

[Brianhardesty]

I can’t find a year, I just know it’s 150 horse

 

[Dukedog]

that's not a good serial number.. if its a V6 merc/mariner it will be 7 numbers or a letter (A, B, C) followed by 6 numbers or a 0 then a letter (D, G) followed by six numbers...

 

[Faztbullet]

You need this....

 

[Brianhardesty]

You need this....
View attachment 395941

Thanks, so I guess there’s a difference in the 90-206-b20 and the 90-206-a20

 

[Dukedog]

gear ratio....