Strong towing numbers and a diesel that actually delivers 28-29 mpg highway, but you're gambling on two expensive failures: the 8-speed automatic shudders and slips toward a $6,000 rebuild, and the AFM lifter system collapses into a ticking mess that demands cam replacement. Transmissions have failed at 83k miles, lifters strike seemingly at random, some trucks cruise past 200k, others need major work before 100k. The GMT800 generation (1999-2006) earned its reputation as bulletproof; the current truck tows competently but trails Ram and Ford in cabin refinement, with materials that don't match the sticker. Budget for an AFM delete if buying new, or find a clean GMT800 and avoid the lottery entirely. Skip this if you want modern interior quality or can't stomach four-figure repair risk.
You're buying a Cummins diesel wrapped in a truck that can't quite match the engine's legendary toughness. That powertrain, especially the older 5.9 12-valve or the new 2025+ ZF8 setup, will tow anything you hook to it and run past 300k miles without drama. Everything bolted around it tells a different story: ball joints that wear like brake pads, electrical gremlins that show up at 2,500 miles, brake calipers grenading before the first oil change. The 2025+ finally got the transmission right, but quality control is shockingly poor for a $70k truck. If you're towing heavy loads regularly, the Cummins is still the best tool available. If you're daily-driving it empty or expecting fit-and-finish that matches the price tag, prepare for disappointment. Buy it for the engine, budget for everything else breaking.