If you are not using the factory pigtail that plugs into that harness, you can change it to any 4-pin connector you want to use. Just buy the matching male and female parts so your pigtail can plug into what you put on the truck harness. I would recommend weatherpak. But you will have to buy the male and female plug sets with pins and wire seals, plus the proper crimp tool for the pins. Then you will have the tool for future projects. Metripack is similar and there are other styles. But those two seal very well against water and dirt intrusion. You can order the stuff easily on ebay, Amazon and many other sites.
Here's a little more info. You may want to scroll to the 39:30 bookmark
I didn't have weatherpak stuff when I made that video. But you can get some good ideas from it.