It looks like your air cleaner has an after-market PCV hose attachment that allows the PCV system to take filtered air from the air cleaner during normal operation. It could also be an OEM air cleaner made for a "Closed PCV System," which is now the standard PCV system. The closed system allows crankcase exhaust to be returned to the air cleaner/intake during acceleration when the PCV valve shuts off. Otherwise, without that air cleaner connection, crankcase exhaust is vented to the atmosphere during acceleration. Closed PCV systems were mandated in 1968, I think, but California may have required them before that. California began retrofitting vehicles with open PCV systems in 1964, if memory is correct.
The early OEM PCV systems were the open type, which Tim's link shows. The pipe attached to the side of the intake manifold is the vacuum connection to the PCV valve, which was a large metal valve attached to the road draft tube. In the In the early days of PCV systems, before emission control systerms, the PCV valve was called a "Donaldson Valve," after the manufacturer, I believe. The first PCV systems were used during WWII on military vehicles to improve engine life, because they typically didn't go fast enough for a road draft tube to work well.
Another bit of history, the early PCV systems were also called a "Positive Breather" system. I think that was more shop jargon than a formal description.
Harvester
