What is the number one plug on a Chevy 4.3 V6?

There's no single "number one" spark plug on a Chevy 4.3L V6 in the way some engines have a clear #1 cylinder designation for firing order. The firing order determines the plug sequence, not a numbered plug location. The 4.3L V6 uses a specific firing order (like 1-3-5-2-4-6 or a variation depending on the specific year and engine code), so you need to consult a diagram or manual specific to your engine's year and model to identify which plug corresponds to cylinder #1. These diagrams usually show the cylinder location and corresponding spark plug wire.