I have a 1993 7.4L that I am winterizing. I can't locate the port side plug to save my life. I've removed all the plugs I can find on that side, but they were all oil gallery plugs. Starboard was easy to find, a brass plug at the base of the block. Where the heck is the port drain?

Same area, keep looking.

Same spot other side and stick a small screwdriver up in the hole while it's draining to remove any debre in the hole and make sure it is open when the water out so you no all the water is out then just pull all your water lines plus the water pump hose too and exhaust water hose's too and fill the engine with antifreeze
here is a sevice manual
www.boatfix.com/merc/Servmanl/16/16cov2_1.pdf