ok so Ibought a cd player for my truck it came out of a 03 silverado its just a stock single disc player, but it beats am fm radio and I dont have the 2000 for the in dash nav dvd. so anyway i unplugged mine and went to plug the new one in and found the cd player has an extra harness connector slot that mine didnt have. is this because it came out of a crew cab truck?? for the extra speakers that the crew cab has? or is there something more that I am missing? any help would be appreciated!