I have a 78 with 231 V6 here in Nor Cal. I am in the same boat as outlawrx in that I am trying to chase down where certain vacuum lines go so I can be ready for smog testing. I have most of it completed with new lines but 2 in particular are tearing my hair out.
Specifically, I am trying to identify this vacuum device that is mounted in the air cleaner housing on the passenger side between the air inlet snorkel and the valve cover breather hose. The device has 2 vacuum nipples protruding from it side-by-side and are currently plugged off. The engine does not run any differently if they are unplugged.
All other vacuum lines present under the hood seem to go to vary specific places. Nothing seems out of place. I have the Chilton manual and it does not detail this device as far as I can tell (or maybe I'm just not understanding the diagram). Also, the vacuum diagram under the hood was missing before I bought the car. And the parts resoration houses don't stock a repro decal for this engine.

Does anyone have any thoughts or ideas on how I can ID this device? Or pehaps tell me where these 2 lines connect to?

Thanks for your help in advance.