If it were 2003 I would take the Dodge with the Cummins, they have proven very dependable in horrible conditions. Ivw known people with tremendous milelage on them and they love them, transmissions are the weakest link in that chain.I worked for a company and we used 2002 Ford F350s, got them brand new, I had one and although they will really pull a load, we had alot of oil related problems such as leaks and for as new as they were and all the miles they had, I wasnt impressed. No experience with the 2003 Duramax, but my friend bought a new 2006 at work and loves it , plus he's getting great fuel milelage around town, in the 20s, I kick the Hemi when I come home, its in the 10s, and does no work but pull my fat A around.