I cannot remember if my stock 318 intake manifold had a vacuum reservoir or not. Anyway my 3rd line just hooks to a vacuum port on the rear of the Offy dual port 360 manifold that is on currently. It has been a long, I mean loooong time since my car has operated but I think when it did, the air control worked Ok. I do seem to recall having to change out the air switch in the dash a few times and seem to remember that was a PITA.