AC Delco Rapidfire #4 plugs in a slant six

Your engine has a solid head and should use the gaskets.

"Drool tube" is a clever euphemism for early slant six's (1962 - 1973?). The spark plugs mount inside removable aluminum tubes. The tubes seal against the head with a large rubber washer that is notorious for seeping oil in poorly maintained engines, hence the term. The washers are available and cheap, so change whenever the rubber hardens.

An engine with good rings and functional PCV should have a slight vacuum in the crankcase, so shouldn't leak since it sucks. A simple test is to remove the oil filler cap when running and see if fumes come out. If a lot, then the crankcase is pressurized, in which case you will see leaks from most crankcase seals.