Weird contraption under dash.....what is it

[woodscavenger]

I have a 62 fleetside. The POs have done some weird stuff but this looks factory but I have no clue what it is. I can't get my cellphone camera to transfer the pic so I'll try to describe it. It is under the dash, attached to the firewall about 2/3 up, right of the throttle linkage and left of center of the cab. It is a short lever about 4" long, 1" wide with a spring to bring it back. When you push the lever it engaged a soft rubber boot that is about 1.5" diameter that goes through the fire wall. On the engine side the rubber device narrows to a smaller hole. What the heck is this??