Correct mix formula - 1/2 water and 1/2 coolant??

When you drain it, flush it with water. Disconnect the 1" rubber hose from it, and stick a hose over the metal nipple that comes vertical out of the back of the cylinder head on the passenger side, it will run out the lower rad hose if you disconnect it. When I flushed mine, some casting sand came out.

Good time to replace the rad hoses (upper & lower) too.