77 Spider Vacuum Component

[wmpwilson]

This plastic component has a vacuum line running to to from the EGR, plus two electrical wires. There is an open Vacuum post facing the passenger side of engine compartment. Any ideas as to what this is/does? Where does the missing vacuum hose come from? Component is marked with a white X, as is the vacuum hose to EGR.

[So Cal Mark]

as I recall, the only switch in the egr system is a thermo vacuum switch that mounts on the intake manifold between the carb and cam housing