1. Consult your vehicle's repair manual: This is the most reliable way to locate the coil. The manual will have diagrams and specifics for your exact truck.
2. Look near the distributor (if present): If your engine has a distributor, the coil is usually mounted very close to it.
3. Look for a relatively small, rectangular or cylindrical component with high-voltage wires connected to it: The wires will be thicker than other engine wires and may have a distinct boot or connector at the ends.
4. Visually trace the high-voltage wires: Follow the thick wires from the spark plug wires to their source. This should lead you directly to the ignition coil.
Without a repair manual, a visual inspection with these tips will be your best bet. Be cautious when working near any electrical components, especially high-voltage ones like the ignition coil. Disconnect the battery's negative terminal before working on the ignition system.