[thelawdoc]

Gentlemen, Please excuse the fact that I did not update this thread sooner. In the passed few months I learned that this knob is not, in fact, the optional throttle control or relevant to any pto. It is, actually, the manual control for manifold heat. I eventually investigated and found that the cable goes to a swivel gate in the exhaust manifold that is directly under the intake manifold. It seems that in cold weather, one may open this gate to facilitate warm-up. Once the truck is warm, one closes the gate. I guess this is what Chevy offered prior to the heat 'stove' that goes up into the air horn. In any event, in the past few months I learned how to tune up my truck, and now she starts as easy as a new Toyota. I never realized just how good a tuned up engine can be, no matter how old she is!