You might want to look at a Dodge with a Cummins in it. There were a lot of changes in the early 2000's. The article below will help you through the technical stuff. In comparison, there were not a lot of the Dodges built and the 24 valve CTD of the era are highly sought after. The "Cummins Forum" is loaded with information.
https://www.allpar.com/mopar/cummins-diesel.html
Ford had a lot of issues during these years, don't know much about the Duramax.