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Thanks for confirming my suspicions Joe about the top drilled holes. Again, last guy really cut a lot of corners on this boat (as in, every aspect of it I'm finding). I'll make the adjustment as per everyone's recommendations.

I agree that the BIA standard for mounting holes are the same across brands. My point was that the lower unit for different motors isn't the same drop from stern bracket to ventilation plate, even within the same brand. For instance, a 1993 40/48/50hp OMC has about 22", whereas this 1993 60/65/70hp OMC has less drop.

The stern bracket pattern is the same, but the lower unit/exhaust housing isn't. So comparing the mounting height of the other guys yamaha to this OMC, it may randomly line up, but isn't necessarily right for the installation. That's why I was asking at the beginning specifically, have folks found a sweet spot for the 70hp OMC motors.

All good information though, thanks again for your help.


(please follow guideline #1 at the top of this page and use the full 4 digit year for everything)