The engines run the same Left Hand rotation. But in the drives you can change the rotation of the props. This changes the speed and handling of the boat considerably (props turning "IN" vs "Out"). The easiest way to see what happens is to just switch the props, and then use the shifters backwards (forward is reverse, and vice versa). Mixing up the forward and backward deal can cause some big damage.
I can't remember the exact dollar amount, but it was way up there.