The supplied headlight switch utilizes convenient connectors for the pre-terminated wiring in the kit, as shown. If you plan to install in the same location as the old one, you'll need to oversize the dash hole just a little. | 
Removing the gauge cluster from the dash will make it easier to wire it later--but more so, it's necessary if you'll be redoing any of the individual gauges. Doing this will require the bezel to be separated from the housing. I suggest it if only to inspect the internal components, but it also gives you the opportunity to restore all the gauge faces. | 
The last "side note" portion of the truck's rewire was providing the proper wiring for the amp (ammeter) gauge. Unlike a voltmeter, it's just an inline tool to read basic battery charge/discharge, but requires the same gauge wire as the battery lead on the alternator/generator (in this case, a PowerGEN alternator). |
In the same fashion as the driver side wiring, the 8-gauge wires for the ammeter were routed through the cowl panel; unfortunately, the stock heater provided some stiff opposition at first, but with a bit of coercing, we were able to feed them through. | 
Since the starter switch has enough power wires running to and from as it is, we ran the battery end of the gauge wiring directly off the battery. | 
This 175-amp Mega fuse should provide a bit more of a safety net than the previous "foiled" 20-amp unit, don't you think? |
The Mega fuse block, which we ended up mounting out of sight up under the dash, runs inline between the alternator and the battery and ignition switch. | 
Unlike before, the back of the gauge cluster isn't clustered with excessive wiring--just the fuel and amp gauge terminals get hooked up. The grey wire, tie-wrapped with the fuel gauge wiring, feeds the instrument lighting (includes lights for speedometer and ignition). | 
And assuming your old dash lights are not quite up to par, the Highway 15 kit comes with new socket terminal pieces for you to build a complete harness section. |