[Richard]

Passenger side engine compartment. My supply line is red and goes into the back of the manifold.

       

Watch this series of videos. https://www.youtube.com/watch?v=7rnRcyW96m4

And read the first couple of pages of this document, it explains how the leveling system, height control valves, and six pack all work together.  https://hwhcorp.com/ml20635.pdf