not a 5th gear, neutral or reverse or a crank, those plugs are bigger. its not a knock sensor plug the knock sensor plug is a 2 wire with a safety clip then goes up to the injector harness and becomes a 1 wire setup.. i might be a cruise control thing cuz none of mine have it and they were just hanging full of grease and oil dirt ect.. theres another one just like it on the passenger side taped where the alternator harness plugs into on the passenger side fender..
dont worry much about it youll be fine..