I'm thinking of buying a new 2003 1-ton 6sp HO dually 4x4 and I was wondering if anyone knew what kind of mileage I would be getting running empty and with a load?

eleventy miles per litre

green_head, Mine averaged about 16 empty if I kept it 70 or below. Loaded it dropped to around 10 to 11. These are pretty much highway numbers.

Hi! I have a 2003 3500 QC SWB with 6sp and HO (305,555) Cummins. I have been getting 17mpg around town and I recently took a road trip where I burned 3 tanks of fuel over about 1800-1900 miles of driving. My calculated average was about 22-23 mpg. Had my family of 4 plus luggage (maybe 750 pounds of people and suitcases/cargo total) making GVW about 8000 lbs on the trip. Sorry but have not pulled a big load with it yet. I just haul a 350 gal plastic water tank with this truck about 3 times per week (gvw @ 10,000 lbs). Not much work for this truck!!! Can hardly tell the difference between the empty tank and a full load of water!!