Does anyone know what these holes are for?

They are only on the port side of the motor and they are threaded, 93 Mercury XRI 150hp

Just curious was wondering if maybe you could mount a power pole bracket there instead of pulling the motor

Mercury.pdf

Looks to me like those holes are to adjust the height of the motor on the transom.  I wouldn't use them to fasten anything to the boat/motor without first checking with a certified Mercury tech.

Powerpole company started business in 1998, the are not for mounting powerpoles. 

Tom

As has been said, those are for motor height adjustment that helps your motor perform better.  As an aside, the older boats transoms are prone to suffer when mounting Power Poles.  Also, I am not a fan of the "sandwich" mounts that go between your motor and the transom.  I have personally experienced them working loose in rough water or long trailering pulls.  Just an FYI.... 

We're not talking about the five holes in the right, but the three holes on the left.  I'm not sure what those are for.  My motor lacks them.

Yes I know the holes on the right of the pic are for motor height adjustment, I'm talking about the three threaded holes on the left, and yes I know they weren't manufactured specific for a power pole, just curious to see if I could use them for that purpose

I don't think so.  I almost feel like they are for shipping purposes, when being shipped from factory.  They come ina wood crate, mounted upright.

I haven't owned a Merc with those auxiliary threaded mounting ears and have no idea what they are used for. Are the ears on both sides of the lower unit? My guess is they are a option to mount a bracket, possibly for a small kicker motor for trolling?

Tom