I have a SeaRay with twin OMC 4.3 sterndrives. Looking at the props, I see
that they turn in different directions - counter-rotating.
I am kind of new to the twin engine scene and had a question that I can't
find the answer to in my manuals.

How is the direction of rotation changed from a "normal outdrive"?
Does the engine "run backwards", or is there a gearset in the outdrive that
changes the direction?
If in the outdrive, is the change in the upper or lower housing? Could you
swap out the gearset in a
"normal outdrive" and make it counter-rotating?

Inquiring minds want to know.....

Thanks in advance....
Bill