Fits models with 12 volt electrical systems and will also work as an upgrade for trucks that have been converted from 6 volt to 12 volt systems. br>Upgrade your headlight's wiring harness for maximum light output with this Heavy-Duty Headlight Harness. If you are adding brighter bulbs or upgrading to high power halogen lights, then you need to improve your wiring to take full advantage of the extra light output. br>This Headlight Harness draws power directly from your battery whereas your original wiring draws its power from your headlight switch. Heavy-Duty Harness is complete with separate relays for low and high beams and features OE style headlight sockets for easy installation with no splicing or cutting required.