Here is what I did:

Get an 8 circuit or 12 circut wiring harness that they sell for just about every street rodder and use that. The 6.2 that is in Grantshire's truck is wired with an 8 circuit one that has everything in it including the signal flasher, and a relay which I used to run the lift pump.

The only electricity the 6.2 requires is the fuel cutoff, idle speed increase when cold, and the glow plugs. Of course the alternator also gets a feed. The rest of the circuits you'll use for the lights, wipers, heater if you have one, and any other accessories.

I picked up the harness from e-bay and its made by Northwest Autowire. A whole lot cheaper than a Painless and just as quality in my opinion.