[BILT4ME]

My father's 68 K20HD had wiper on top left, headlights lower left, Choke top right, and throttle lower right.

The throttle on that truck (originally K20 4 speed, 292) was a "ratcheting" type where you would step on the gas pedal to increase the RPM and pull out the cable a notch at a time until you got it where you wanted it. It could hold it at WOT if you needed it to.

We would put it in low range, 2nd gear and set the throttle, then walk across the hay field while picking up hay bales and throwing them in the back. Leave the window down so you could make steering changes while it drove itself across the field.
We would also do it for dumping hay and feed to the animals in a pasture (when only one person was doing it. Set the throttle, climb out the door and into the bed, scoop out as necessary, then climb back in, all while still moving, slowly of course.

This "early" version was attached directly to the carburetor linkage and wwas an additional cable next to the throttle wire with a cable stop attached to the throttle cable. It was designed to have the stop slide forward and back on the wires during normal use, but the throttle cable would limit the RETURN of the butterfly to the closed position, thus, holding the butterfly open.

To "disengage", basically you had to push hard or "punch" the throttle button to shove it back in. As a kid, I had a hard time pulling it out, but to push it in, I literally punched it with an open hand.

I installed one on my 69 Chevy (non-factory) that I could pull out, twist to the right to lock it, and that was my poor-man's cruise control...........