No new harness yet. Just put new battery cables, 2 guage, and used a new 10 guage wire from single wire 65 amp alternator to the battery terminal on starter. Had to change the pulley on alternator to a 201-01005 from J&N Auto Electric catalog, or a 24-7100 from WAI catalog. Also Changed lights everywhere, put the resistor on fuel guage. Don't have any other electronics yet. I did change to Pertronixs ignition and 12. Volt coil at same time. We'll worth the money. Starts right up, headlights way brighter. I like it.