If the rod runs down the handle and through the ball into the trans itself, it is a reverse gear lockout; there was a lever on the shifter just beneath the knob (there should be a hole for a pin or a screw through the handle about an inch or so below the knob), and you could hook it with your ring and pinky fingers and pull it up to move the handle to the reverse slot. Otherwise, it should be a cable of some sort to operate a two speed rearend or an overdrive unit. The switch??? I thot maybe a backup light switch, but on second thought, that wouldn't be it, because there are no external levers on that trans, and it is not hefty enough to be an operating solenoid, considering the age of the unit, and the level of technology at that time.