Mercury lower unit interchange

[Jon Sloat]

Hello fellow Boaters, Hope this post finds you all well, I just purchased a 1986 Mercury 115ELP that needs a lower unit. I'm having a bit of difficulty finding an interchange chart (if there is one) so I know what year will work. I know there are different gear ratios but the engine I purchased has 1/2 of the gear case missing along with the prop shaft. I do know that the drive shaft has 8 splines and is 22-1/2" long. Any help you can share would be greatly appreciated. Have a great day

 

[racerone]

An in-line 6 cylinder ?

 

[Jon Sloat]

Yes it is an inline 6. The tag on the lower unit is 0A163525. Sorry I did not reply sooner but I haven't figured out how to get e-mail notifications on my phone when a reply is posted. Thank you for the reply, it is much appreciated.

 

[jimmbo]

Since 1973 all inline 6s used the 2:1 ratio, and will fit your engine. The post 1978 cases have more sweepback in the skeg and are a slightly better at high speeds. Just make sure the unit is for a long shaft.

 

[Jon Sloat]

Thanks for your reply. From what I understand, there is a certain year that they changed from a 3 jaw to a 6 jaw and the shift shaft is different, When they speak about shift jaws I am assuming they are referring to the clutch dog. The drive shaft has 8 splines. I guess what I am looking for is what year and HP range will fit this motor. I'm very surprised that more people didn't pick up this post and offer advice. I'm thankful you did and appreciate it. Thanks again, Jon