My 1946 2 1/2 ton truck has been sitting here for a couple years now, so I am planning to finally get some work done on it this winter. The first thing I need to do is a COMPLETE re-wire. It's still OEM and no telling how good of shape it's in. I also want to convert to 12 volt. Anyone have a diagram or drawings handy so I can make my own harness?

There is a write up in the Tech Tips section on how to convert to 12 volt

http://www.rebel-wire.com/

These people are advertised in another section and there is a discount for Stovebolt members.

With the cost of bulk wire and wire connectors these days the pre-made wire harness is about as cheap as making your own.

I've actually got access to wire/terminals, etc. All I need is the "map".....

I'm a little late to the game, here, but you can get a reprinted copy of the shop manual that will help (if you don't have this figured out already).

Try going here: http://chevy.oldcarmanualproject.com/

There is a 1947 wiring harness shown.