Draining the radiator

I remember reading about some of the Chev/ GM stuff built in the late 70-80's. Not only did they not put block drain plugs in some engines, they didn't put rad drain cocks in 'em, either. Only way to drain them was pull the lower hose or siphon out of the side tank, and then knock out a frost plug on each side. I vaguely remember you could buy special freeze plugs with a drain boss in them.