1. Identify your engine: Look for a sticker on the engine itself or in the engine compartment (often on the radiator support) indicating the engine size and type (e.g., 4.2L V6, 4.6L V8, 5.4L V8).
2. Find a diagram: Once you know the engine type, search online for "[Your Engine Type] firing order" or "[Your Engine Type] cylinder location diagram." Many websites and forums dedicated to Ford F-150s will have these diagrams showing the cylinder locations. The firing order helps determine the location from the number.
The cylinder numbering varies by engine configuration. Don't rely on a generic answer; you *must* find a diagram specific to your truck's engine.