Except for the cruise control switch that failed early on and the really poor tires that were provided I have had zero problems with my GMC 3500 long bed duramax allison crew cab dually that I purchased in 2005. My GMC has largely been used for hauling trailers, including my 35 foot fifth wheel, a car hauler and a 20 foot box trailer. The diesel never falters, even on fairly sharp inclines. And compared to Ford or Dodge the engine remains quite quiet.
It's a beautiful truck, feels like your riding in luxury. We have the TV/DVD package and that works great for our 4 kids who fit comfortably in the back on long trips. Good on gas for something that size, always runs and drives great. Have also used it to pull out the tractor when it got buried plowing the field, was not a problem it came right out and the truck barely had to try. Also pulled out a boat hauler that was stuck in a field, no limit to this truck.
I have to say my experience with my GMC has been awesome. I have travelled over 17,000 miles since I first got it. It hauls my 42' 5th wheel with no difficulty and my daughter enjoys the DVD system w/the wireless headphones only a little more than I do. Great sound system and entertainment system. Shocks are a little stiff but only when I'm not hauling. I did a lot of comparision shopping and my GMC had the most options for the best price.
i have 4000 miles on gmc3500lly 04 duramax allison crew cab dually, half of the miles is towing ,it gets 12 to 16 mpg, the motor and tranny handles the weight easily ,i have a bw gooseneck hitch to haul a 14000 dump trailor, sometimes going up and down 6% grades, the transmission downshifts automatically,its easy on the brakes when towing ,it dosent ride like a truck and its very quiet for a diesel its fun to drive and get lots of compliments on how the truck looks and when taking people for a ride in it they enjoy it ,i owned a dodge dikota a 2500 silverado and a heavy duty silverado 2500 and a heavy duty 3500 chevy chassis cab with a dump body i like the gmc 3500 the best
The comfort and drivabilty beats the Ford 350. I had an '01 F350 which was a great truck, but had some reliabilty problems and the brakes were not up to the task. The GMC is much better overall with towing and the interior is more car like. My biggest complaint about the truck is the gray steel rims with cheap trim rings. For over $40K the truck should be outfitted with Ford/Dodge similar rims. I almost went for the Ford again because of this.