So I dove a little deeper (I’m tearing apart my car anyway to do a communications install) and found where everything goes.
It goes from the first white canister after the one way valve down to the big canister underneath the bar.
From there it comes out the other side of that canister into another small white canister seen on the right side of the bar.
Then heads back up and out to the frame like the rest of them do. But also there is a second hose that comes off the back of the big canister and runs to that solenoid you see on top of the bar, and then out and up following the other vent hose to god knows where.
So at this point I don’t even know if installing that valve would do anything.