I don't know about Ford and Dodge, but Chevy didn't offer a 4x4 one ton dually until 1977. Even at that, sales of 4x4 models were slow...
In 1977 only 60,779 one ton trucks were made, and only 8% of them 4x4. That's 4,800 4wd 1 tons. Not many compared to 110,416 1/2 tons made that were 4wd, and 12,054 3/4 ton trucks that were 4wd.
In 1978 only 68,010 1 ton trucks were made, this, vs. 540,968 1/2 ton trucks, and 176,735 3/4 ton trucks. No percentages for 4wd models were given in the book I have for 1978.
Don't want to bore you all, just making a point that 4wd wasn't common on 1 ton models until later years. I had a friend that plowed in 1996 with a 95 Ford F-350 12' rack body, 2wd. In the middle of the winter, in the middle of a storm, he was out buying chains for it. He got tired of getting stuck. Needless to say in the spring, he traded it in on a 4wd rack body. He thought like most other landscapers, "I don't need 4wd" when he bought it, and maybe wanted to save on cost. WRONG. You don't need it if you don't want to plow. Yes, you could have a V box on the back, and ballast at all times. But who wants to increase fuel consumption, as well as wear on the truck, just to not get stuck?
~Chuck