I find that the easiest way for me to do a universal harness is to lay the old one out on the garage floor. Spread it out in roughly the same layout as if it were in the truck. Use the wiring diagram and go through every wire and label every stinking wire so that you don't forget what it is. Lay out your new harness in the same shape/layout. Then identify the corresponding wires in the new with the old. With care you can cut the wires to the proper length add the connectors and tape it up there on the floor.
There are two dashes and both have a plug that plugs into the back of the inst panel. Yours has gauges (it would seem) and the other has only idiot lights. The differences can be a mess on some diagrams.
On my '67 the Amp wire goes across the top of the radiator. One of those small fuses is located on each side of the radiator. There are other things to look for. There is a resistance wire that goes from the firewall connector over to the Ign switch. You would identify it by following the wire from the #3 on the regulator plug, into the firewall connector and it's on the other side. It isn't copper, so it can't be soldered.
