Air cleaner housing missing a connection

[gr8dane]

Just got a '87 Jimmy from a state with no inspections, and I live in an oppressive state the requires all original parts to be there, so I am in the process of finding parts like the air pump etc...
I know I need the pre heater duct for the air cleaner, but I can not figure out what this connection is for, and where it is supposed to connect to

Any help would be awesome

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[PrairieDrifter]

That is part of the pcv system. It's just the fresh air filter, there's a small filter in there that's missing a clip, and then it goes to
the passenger side valve cover.

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[75gmck25]

This picture below is the filter and clip. Then you need the valve cover fitting, which is just a short metal connector, and the short hose that prairiedrifter shows in his picture. A visit to pick and pull will get you a valve cover fitting the quickest, since they were used on many GM vehicles.