Slider switch on acc. pedal?

[1970CustomC10350]

Hello everyone! I was poking around under the dash checking some wiring on our 71 3/4 ton tonight and noticed some kind of slider switch attached to the acc. pedal linkage. It has two wires running to it. One comes from the fuse box and the other goes out to the engine compartment through the firewall. I'm wondering if it was some kind of cruise control or something like that. Any ideas?
The truck was originally a big block with fac. air if that matters.

Also does anyone make a replacement throttle control that mount to the instrument cluster? I'm pretty sure all I need is the knob. Thanks!