This one-owner, locally owned, accident-free 2025 GMC Sierra 2500HD AT4 in bold Onyx Black is a premium heavy-duty pickup engineered for serious capability, luxury, and off-road prowess. Powered by the Duramax 6.6L V8 Turbodiesel with a smooth 10-speed automatic and robust 4WD system featuring a 2-speed active transfer case, Hill Descent Control, and the X31 Off-Road Package, it offers massive torque, exceptional towing power, and enhanced trail performance with increased ground clearance. A fresh oil change has been completed, and it stands out with gloss black accents, LED smoked amber roof marker lamps, spray-on bedliner, off-road steps, and LED cargo lighting. The upscale cabin features Jet Black with Kalahari accents leather, ventilated and heated front seats, heated second-row seats, a power sunroof, Bose premium audio, a massive 15" head-up display, wireless charging, and advanced trailering/safety tech. Loaded with the AT4 Preferred, Premium Plus, Technology, Max Trailering, and Gooseneck/5th Wheel Prep packages, this top-trim Sierra 2500HD AT4 is the ultimate powerful, refined, and trail-ready diesel workhorse.