That hasn't happened. I bought the truck from the son of the original owner. It was purchased new for use on the farm and according to him it was ordered as a cab chassis. His Dad had the dump bed installed.
In looking at the notes at the bottom of the spec page for Vin identification is the following.

Series # with "S" = "Special Model"
Series 31-3200 = Light Duty
Series 34-35-36-37-3800 = Medium Duty
Series 40-50-60 = Heavy Duty

So.. It seems like these trucks could be ordered in 1 to 2 ton capacity in various iterations.

Is this correct?