Each and every wire has a metal tag with a number on it.. they are the same for all MV.. The codes are available in many forums, but of course they are in all the manuals, too...If you are towing a civvy trailer you only need 4 wires and you can just find em with a test lite and use quick connectors to a flat 4 and off you go.... after you change the bulbs to 24 V.... ACE