I did my 65 dart from scratch by setting the harness(es) on the floor and making a new one next to it, a duplicate for the most part, I lengthened some wires as needed and went to a larger gauges on some as needed. crimp/solder/shrinkwrap one wire in & cut the old one out of the old harness till the new one took shape and the old one dissappeared. there are sources that will sell you the exact lengths of wire you need & #1
#1 #1 use the same colors including colors with tracers that Ma used. it was ALOT of work even on a bare bones 65 dart but it should be trouble free for a long time if I keep the ammeter needle close to 12 0'clock and if I do add extras that I relay em directly to where they will be fed from which is the alt