Therefore, the number one spark plug wire on the distributor cap will connect to the terminal corresponding to the number 1 in the firing order. The distributor cap itself may have numbers on it showing the cylinder number. If the numbers are present on your distributor cap, look for the "1". If not, you'll need to trace the wires, or use a reliable diagram for that specific engine. A repair manual for your truck would be the best resource.
Important Note: The location of #1 may vary *slightly* depending on whether the distributor is rotated slightly. It is best to consult a 1985 F-150 repair manual or a reliable online diagram for your specific engine and distributor to be absolutely certain.
