I agree with Ed. On my 1948 GMC 1.5 ton, there is one lever just to the right of the shift lever, it is the e/parking brake lever, it has a release handle. To the left of the shift lever, and further back toward the seat, there are 2 levers on one pivot, one engages the PTO, the other engages the dump. Yours may have one lever on that pivot to engage the PTO. As suggested above, follow the linkages and let us know what you find!
