Used 2004 GMC Sierra 2500HD Consumer Reviews
Absolutely the best truck I have ever owned. During it's maiden break-in run I got 23.8 mpg. When engine is broken in mileage should be even better. I drive between 55-65 mph and this seems to be the "sweet spot" for performance. Got it to haul our slide in camper and this will be no problem now. (Not like our 91 Silverado which on it's best day with only one person got 20 mpg)
Truck has been overall a good unit. Windsheild leak when new at passenger floorboard and behind dash. Took 1 year for local dealer to finally fix. Climate Control slow to activate fan, really noticable on hot days, seems I have to press brake pedal to start blower (wierd). Trans will sometimes start in 2nd gear, then shift to 1st. Usual problems with intermiediate steering shaft (now on 2nd fix), driver's seat belt and armrest broke, pass side also (wrty fixes). Also having wierd problem during cold months with intermittent dash light and guages recycling, no fix yet. Orig brakes are still strong at 90k miles, tire wear good, body still tight and quiet, engine strong with no oil usage
I have the 2nd generation LLY Duramax engine in mine and i love it. I had to replace the injectors when i bought it at 130,000 but other than that i have just been upgrading. The ride is great, the seats are comfortable, the fuel economy is good, 20-24 highway, 15-18 city, if i keep my foot out of it(hard to do with 400 HP and 600LbFt of torque on tap). I have not had any major breakdowns since owning it. The transmission did blow up at 143,000, but it was a freak electrical short that caused it to engage 2 gears at once(lots of chunks in the pan). It actually got me all the way back to the shop in limp mode which was about 25 miles, 10 of which on a logging road.
The experience of getting better gas milage with the 6.0 motor in the GMC as opposed to the 4.8 in my Chev, makes me wish I had bought the Chev with the 6.o instead of the 4.8. Factor in the added pulling power, makes it far better. I highly reccomend getting the 6.0 in either model truck.
Traded in my 96' GMC 3/4 ton Suburban, w/ 454 Vortec engine for this new crew cab, Duramax w/ Allison transmission. Wow what a difference in towing power. Previously driving over mountins into Prescott and Payson, from the Phoenix area, we were lucky to keep up 35mph. Now, wow, 65mph over the same roads and mountains, towing the same trailer. Diesel milage is better than the gas by about 5 to 6 mpg. Wish the Suburban had this engine/trans.