1984 C10 Vacuum question.

[ndbrownknives]

Hello all. I am new to the site and was reffered by my local auto part store mgr. I have an '84 LB 2WD AT 305ci. I had to redo all of the vacuum lines when I got the truck which I was able to get straight from a vac diagram, but I have two vac switches on the fire wall I can't figure out what they do. There is one vac switch on each side(passenger/driver) of the firewall. Each has a vacuum nipple on one side and two wires plugged into the other side. Does anyone know what these do and where they should attach to vacuum. Any help would be huge. Thanks to all of you.