Can I swap a body off of a 1956 1-ton F-100 (I'm pretty sure it's a 1-ton.........it sure looks like it) on to a 1976 1/2-ton F-100?

 

The question is do you have the ability to do it? Measure, take notes, and measure again. Cut weld and cut some more. Planning and desire have to be key to completing a project.
I am currently cross-breeding a truck, '52 REO cab and a '73 F250 4X4 running gear. I've got a long way to go, but getting there is fun.
Consider the length of your project, and good luck.