Find a 2006 and don't look back. Easily the most reliable diesel PU ever made. The magazine Turbo Diesel Register prints pages of issues for each generation of Dodge diesel truck. Most generations get three or four pages of issues. Usually small things. But the GEN 3 trucks don't usually get a full page. This is when Mercedes owned Chrysler and lots off attention was paid to the truck line.
But you'll pay big for a 2006 with reasonable mileage and in good shape. If you can even find one for sale!
I have nearly 200K miles on mine and only issue has been a water pump, AC compressor, Exhaust system (cat back) and a recall for front steering stuff. No other isues...Fuel, Oil, Brakes and tires