We don't have enough information to work with. What year and series is the truck you're working with? The wiring harness in your link is designed to fit a light duty truck such as a pickup with an original equipment alternator with an external regulator. That Leece-Neville alternator was usually used on heavy duty rigs such as tractor trailers, fire trucks, ambulances, and other vehicles with a lot more electrical accessories than the average truck. The 4 pin connector does not need any connections at all, since the alternator it was intended to work with is not being used. Please give us enough information to be able to help you.
Jerry
