Loaded up the '03 Cummins (with 218k miles), hitched up the biggest U-Haul enclosed trailer I could rent loaded with furniture & my daughter's sundry possesions, chocolate lab on the back seat, and left Canton Ga for Wellington Colorado. Travelled a total of 3867 miles in 9 days, 1500 of those miles towing the trailer. Average fuel mileage for the whole trip was 18.0 mpg, 15.9 going up, 20.1 coming back. While there, drove around a fair amount & visited with some Campfire friends as well as a trip out to the bison ranch outside of Lusk Wy. Had a freak thing happen on the way back. At my second fuel stop in Illinois, I noticed some fluid had coated the tailgate. Checked & found the transmission had developed a leak from the bellhousing. Took about a quart of fluid to make it back home. Got the truck back to Garmon Diesel as the tranny was under the Suncoast warranty. They found that one of the oil pump ears on the torque converter hub had developed a hairline crack and had damaged the front pump seal. I was very fortunate that the ear didn't break off, or I would have been on the side of the road somewhere. I guess almost 1100 lb/ft of torque is pretty hard on things (140k miles on the TC). Garmon took care of it, no questions asked. A class operation.
