Your International B120 3/4 Ton electrical system relies on a variety of specialized electrical components to do its job. From the voltage regulator that controls how much electricity the alternator makes (like a generator), to the starter solenoid that handles the job of energizing the starter motor. A maze of wires run through the wiring harness, through the fuse box (or fuse block) and out to all the various electrical systems. Today's modern hybrid battery technology and even Optima AGM (absorbent glass mat) batteries can offer more power than ever, but still need a properly working electrical system to have any benefit. When the headlights won't light or the car won't start, you need quality parts you can count on. Visit your local NAPA Auto Parts for all your automotive electrical needs including battery testing and warranty replacement.