1959 Panel, dual wheels...from factory?

[howard.peters]

Found an interesting picture on the web, from 1966. I took a screen shot and cropped out the unimportant stuff. The truck shown is, I believe, a '59 Chevy panel with dual wheels. My question to all you experts out there: was this a factory built truck, do you think, or built in a custom shop?

I have looked at a document downloaded from the GM Heritage Center, called 1959-Chevrolet-Truck.pdf. This seems to show that dual wheels, 19.5 inch, were available on at least some series 3800 trucks. I have never before seen this on a panel truck.

After doing some googling, a few pictures and articles were found showing one ton panel trucks with duals. One from the 30s, one from the late 40s, a couple from early 50s, one 1957. All either appeared to be or were said to be factory built. Needless to say these are quite rare since few were made and they were generally worked to death and then scrapped.

Opinions?