[reelfishin]

I picked up a boat the other day which was garage kept for many years, probably since new. The boat was parked after the lower unit seized many years ago. I pulled the lower unit, and gave the motor a good once over and a compression check. All looks good.

Now for the question, I have a few good used mid to late 60's Mercruiser lower units that sure do look the same other than the drive shaft. The lower units were all from Merc 110 and 120 I/O drives.

Can I swap drive shafts and use one of them on this motor?

The prop hub and housing diameter is the same, the bolt pattern looks the same, and the shift linkage is the same. I guess the main question would be gear ratio and the ability to install the outboard drive shaft in the I/O lower unit?

[hamit59]

Well the case could be the same but the ratio will not be. That would likely 1:1 as the ratio is set on and i/o in the upper. one on e bay you have all winter i have seen them on there before. there's always criegs list. I have found a lot of parts motors on there also.

[reelfishin]

If the case is the same, that may be good enough, the case on the 850 is pretty well worn and pitted, the I/O cases are are all mint.
I've been told by several sources locally that they swap with no problem and by others that it's a no go. I know it will mount up and use the same prop. It's the ratio that will be the issue. I can change prop pitch, and a higher ratio may not be a bad thing since this motor is on a super light boat. I may be able to make even better use of the torque from the inline 6.