Having a hard time finding some good pictures. Here is one on Jolly's site:
http://www.6066gmcguy.org/Bmodel.htmScroll down to the 2nd picture of the yellow truck. Click on the picture for a larger view. It is a "B" model, but it has the same roof as your truck. Notice the style of horn on the truck next to it is different. If I was still driving the '62 GMC 6500 I used to drive, I could take a roof picture for you. There are a few truck owners on here with factory '60 to '66 air horns, but very few.
Bill
