Green antifreeze or coolant as some call it.

Bills65Dart said

Well, the radiator is copper, and I assume the heater is too. It is not connected at the moment, for whatever reason. But the tubes that comes out of the firewall is copper.

The question about overflow and that stuff, I have no clue. It is a stock 1965 Slant Six radiator.

Bill

Click to expand...

Not a huge Wal-Mart fan, but you can't argue with their pricing. Get a gallon of antifreeze, and distilled water.
You do not have an overflow tank, just a tube running off the radiator to the ground. When filling your radiator, it should be about 1" below the top of the radiator. Allowing room for expansion. While you are at it, it wouldn't hurt to pick up a new Stant rad cap.