The GMC CCKW

I am looking for more information and source for the fron wiring harness. The rear harness terminates at the blackout switch and runs to the taillights. The front harness terminates on the black out swithc and runs to the lunestte with the heavy four prong male plug.

I have a 7 foot cable with cloth covered loom and with two male plugs attached. What is this ?

Does somebody have good pictures of the wiring harness?

Thanks~