You won't find a separate box or switch; it's a small switch that's part of the mechanism. To access it, you'll likely need to:
1. Remove the clutch pedal access panel: This usually involves removing the lower dash panel below the steering wheel. Refer to your vehicle's repair manual for specific instructions.
2. Inspect the clutch pedal assembly: Once you have access, look closely at the pedal's linkage. The switch is usually mounted on or near the clutch pedal and will be a small electrical component with wires attached. It might be incorporated into the pedal linkage itself, or be a separate switch mounted nearby.
Caution: Working on your vehicle's electrical system requires some mechanical aptitude and knowledge of safety precautions. If you're not comfortable with this, it's best to take your truck to a qualified mechanic. Incorrectly working on the clutch safety switch could lead to problems starting your truck or other issues. A repair manual specific to your year and model Ram 2500 will be extremely helpful.