I believe your model would be a C30MB- which, if correct, would put your starter on the lower right side of the engine (as seated), with the solenoid mounted on the starters top or bottom (depending on the mounting). The neutral safety switch is mounted on the top of the trans- close to where the directional linkage attaches to the trans.

As stated, most times a "clicking" is low battery voltage to the starter. I personally by-pass the electrical system of the truck altogether by using a jumper battery directly to the starter (with the unit's battery disconnected) to test the starter. If the unit turns over well with the jumper battery set up, then a connection issue is present in the wiring of the unit.