All three diesels (Dodge, Ford, & GM) pull real good, but is my opinion that GM makes both a better truck and uses a more reliable engine, period. Take a look at the other forums, they have lots more posts, there is a reason for this.
Between me and my dad we own all three brands, chevy wins on reliability hands down. I have learned to never buy a diesel truck the first year of introduction of a new engine. with this in mind, when you look at the other forums, look for resolution of certain reliability issues by truck makers. If you look realisticly, you will see a trend. The trend that I see, is that GM has done a much better job of resolving reliability issues than either Ford or espscially Dodge.
I own GM products, why am I spending time on the Dodge and Ford forums? I am doing so in order to find resolution for my dad's issues with his Dodge and his Ford. I do not post negative remarks about these brands on their respective forums, thats not right.
I got lots of good info from the Dodge forum in the diagnosis and replacement of the Cummins injection pump, (2002 Dodge at about 30,000 miles). I got some perspective at the Ford forum in dealing with waranty issues with my dads 2004 Ford, which has had many issues with turbo and injectors. He had to start lemon law proceding in order to get the dealer to work thes issues out, but still these issues have not been properly addressed.
I have a 3 Ford work trucks with the V-10 gas (the price was right!), which have proved to be good trucks, but at this point I would not buy a Ford Diesel. The Last Dodge I bought was in 1990, the cummins motor was the best thing going at the time, but the drive train was problematic. Two expensive transmission failures, 1 rear axle failure, and some front end issues. Both transmission failures were under waranty, but dodge would only cover 1/2 of the first, and none of the second. I didnt even try waranty on the axle. (waranty was 36,000 miles). Yea, this was a long time ago, things must be better by now right? but I still remember.
Keep an open mind, check things out, and the answer will come to you.