http://shbox.com/1/opti_vacuum_conn.jpg

Does this picture help? Is this what you're talking about?

 

Thanks, but no. I believe that is the oneway check valve. I'm looking at the other plastic fitting (larger) towards the front of the valve cover, on that same hose the check valve is on in the picture just about 8"-10" further forward.

 

I think it matters for both, obviously the check valve.
and also the restrictor, I think thats the one that has a filter in it to help keep the passage unplugged.