I finally came across a manual that shows the 65 66 single headlight trucks. This is for the Right Hand Drive truck but I looked at the wiring diagram and compared it to my 66 wiring harness and it looks the same to me except being reversed sides of the truck.
I have them in pdf also if you want the pdf PM me with your email addres and I will email them to you.
65 66 520
67 68 520