Try a search in the archives on Eaton to swap the chunk to a 4.10.
Is there such a thing as a lighter duty dually rearend? I don't think so. A one ton rear is a one ton rear as far as duty goes.
You can swap it out with a dually full floating 14 bolt from 73 up and get some taller gears that way, it will be close in width. I have seen some dually's out of diesels with 3.42 or 3.08. Most of these have 4.56, 4.10 or 3.73 that I have seen.
You could swap it with a 9 1/2" semi floating 14 bolt and put dually adapters on it or run it with single wheels and that would be a lighter rear end with newer brakes, smaller drums and a smaller pumpkin with 8 lugs. These are easy to find with 3.42 gears.
