PS
the one on the port side for the pivot housing/raw water hose you will usually get water from, you may have to rod it out with a pic
the ones on the starboard side (there are 2) are there in case either the gasket between the pivot housing and drive leaks, or if the threaded fitting for the shift cable that's screwed into the back of the pivot housing leaks. Mine usually does not have water there but it's still good to check.
I add antifreeze, I feel it helps reduce corrosion but that's optional. I use Sierra PG antifreeze mixed up to provide freeze protection to about -30*F. Better than RV antifreeze by far.
Make sure to rod out all drain holes including the ones in the engine and exhaust manifold, they can be blocked by rust flakes.
PPS if those drains on the side of the pivot housing are seized up (can happen if never removed) try an impact screwdriver, if they are really stuck you can remove the 6 nuts that hold the drive to the pivot housing and pull the drive back a bit, that will let any water drain. Trapped water can and will crack housings.
