There are several threads going on about wiring and wiring harnesses. Besides the usual "it is your truck, do what you want and can personally afford" discliaimer. I thought I would go over a few things.
3 lever switches are the heart of the stock wiring system. Besides the alternator, batteries and on/off switch. The light system is the stock wiring. You will need at least one spare. I went through 3 used ones until I got one that worked.
Here is the schematic I like to use when referring to any light issues and wiring.
http://www.m715zone.com/vb/pages/man...g/lighting.pdf
E-Bay is a good source for 3 lever switches. So is Saturn Surplus, Memphis and AB Linn.
One place I found that has all the switches, wiring harnesses, Pachard connectors, wires and turn signal stuff is Star Ordnance. Call Keven at 270-877-0813 and he will fix you up. He even has the water proof military 24 V Chevy V8 distributors for around $250.00.
I started a thread a few weeks ago about using a new M35A2 wiring harness on the M715. I am still going to persue that. They just have been jumping from around $50 to $150 in the last few hours of the auction lately.