GMC sported a closed crankcase breather system. here are a couple photos from my 46 resto. Note the breather tube plumbed into the intake from the valve cover. The moisture and crankcase gases pass through an evapotransfixerator (PCV valve) just before the intake where they are recycled that also includes a disposable baffled filter inside the canister on the upper breather tube.
This would be the same principle as found on 261’s and correct for a 6 cylinder GMC 228-248-270 and possibly but unsure a 302 (military 302’s also had a closed system where a snorkel was added with a similar but more robust down tube canister.)
The last picture shows the builder in fast action mode. Note the blurred hand movement. This comes with practice (some humor to add some brevity to this outstanding message string )
(Look what you started Staggerlee… it can only get better, or worse depending on you point of view… welcome aboard)
