Re: 4.3 engine block plugs
You can use the plastic blue plugs that are used on some Mercruiser blocks, but I would stay away from using petcocks or hoses. You need to be able to put something (stiff wire) in the block when you winterize it to break up the deposits that form over the plug hole. Petcocks and hoses clog up and you run the risk of not getting all of the water out. The best thing to do is to Keep it simple.
Its always a good idea to run the engine on the muffs after each use, especially after salt water use. Running the engine washes away dirty water out of your water pump and thermostat...