The 2002 E150 with the 4.2L V6 engine has its cylinders arranged in a
V-formation. There isn't a single "cylinder 1 location" in the same way an inline engine would have. To find a specific cylinder, you'll need a repair manual or a diagram of the engine. These will show the firing order and cylinder numbering. The firing order dictates the sequence of combustion, and the numbers are usually cast into the engine block itself.
Typically, Cylinder #1 is located at the front of the engine, on the passenger side (right side in the US) when looking at the engine from the front of the vehicle. However, it's crucial to verify this using a diagram for your specific engine. Without a diagram, it's impossible to be completely certain of the position.
