What damage can occur by not having the cable connected? I couldn't find a replacement cable today at the parts store I was at and won't have the chance to go out again tonight.
FWIW, I assume electronics are involved in the lockup on this tranny, because if you press the brake pedal hard enough to get the brake lights to come on while maintaining speed, you can feel it unlock and the engine speed increases.
I've almost got my '86 K5 back on the road. Just gotta make a few more wiring connections, replace a few vacuum lines, and put the distributor cap and plug wires on it. I'm close! :-)
~jp