You will find many differences in the running gear and the frames are diffrent in shape and dimensions. You can buy almost every part new for the 1/2 Ton, but not the 1 Ton.
Now on the front fenders, I have been getting two different stories on that. Some will tell you that the fenders are the same and some will say that they are different. I noticed that Jim Carter had an AD fender for sale on Ebay that was described as fitting the 1/2 Ton and 3/4 Ton. I would be interested to know if your fenders measure out the same. I know that my 1 Ton is wider at the front than the 1/2 Ton, including the bumper.