This is on the drivers side. There is one on the psg side that connects to the charcoal canister. I think this tin is off a '73 1.7 and this is a 2.0 GC case.
Click to view attachment

Click to view attachment

I believe that has something to do with the charcoal canister for the gas evap system.
Tom

That is picked up on the other side which has the identicle sized port. My 76 is connected the same way, however it doesn't have the extra port on the drivers side like this one!???

On my 74 2.0 that line goes from the engine tin (DS) to one of the two plastic pipes that come from the firewall up in the corner under the relay board and blower motor...

Then again, my charcoal canister is up in the front trunk...I can snap a pic if it helps.

There's always the vacuum diagrams on Bowlsby's site...thinking it's just a different model year thing...could just cap it.

Thx eric, I probably will just cap it. BTW, where does the one on the psg side go to if the dvr side hooks to the cannister. Ditto, I assume. If/then, one side must be + atmosphere and the other - atmosphere. If my assumption is correct then the aircleaner on the 75-76 has an additional opening to to replace the one I show. Would make sense in that the canister is relocated to the engine compartment (which I did on this '73) on 75-76 MY.