69' Merc 125HP & 74' Merc 115HP Do Lower Units Swap?

riddert

Cadet
Joined
Sep 28, 2009
Messages
21
Hello all... Hoping to find some info on my old mercs. I have a 1969 125HP that has a great powerhead but the lower unit casing is cracked. I also have a 1974 Merc 115 not running but has a nice lower unit. Will the 1974 gearcase fit the older 1969? I am pretty sure they will swap but looking for a confirmation from someone who knows these old motors really well.

Also, will a blue band control box work on the red band motor or do I need a red band control box for the 69'? Looks like the male/female connections are the same on both motors.

Many thanks to all of the great people who contribute to this board!
 
Last edited:

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,931
Re: 69' Merc 125HP & 74' Merc 115HP Do Lower Units Swap?

All the inline 6 units are 2:1 ratio except for the 1970-71 115 & 135 which are 1:78 units, so the 74 will bolt on nicely just gear the crankshaft splines good. The 74 and 69 use the same switchbox so it should not be a problem...
 

riddert

Cadet
Joined
Sep 28, 2009
Messages
21
Re: 69' Merc 125HP & 74' Merc 115HP Do Lower Units Swap?

That is great and exactly what I was hoping! You do mean to grease the crankshaft splines and not "gear" them correct?
 
Top