I would look at the socket and see that there are 2 contacts in the bottom. If not, then you can only use an 1156 lamp (1 filiment). The 1156 will only work as parking
or blinker. You'll need to use a socket with 2 contacts and use an 1157 lamp (2 filiments). If you go with the 2 contact socket, you'll need to run a wire from your switch for "parking lights". I'm not sure what came stock on the truck...I would think it came with blinkers and not parking lights. My truck has been re-wired and I can't remember what I had before the re-wire job. When you connected all the wires together, you've created continuity between all the other lights, thus making them all flash. I hope this was some help to you..
