The upcoming 2026 GMC Sierra HD will introduce only minor updates and changes compared the preceding 2025 model year, including a new paint option. Now, GM Authority has learned when production of the 2026 GMC Sierra HD will officially get under way.
According to sources familiar with the matter, the start of regular production (SORP) for the 2026 GMC Sierra HD is currently scheduled for August 11th, 2025. This includes all three body styles (Regular Cab, Double Cab, Crew Cab). Dealers can begin configuring the 2026 Sierra HD online on June 12th, 2025.
Only minor changes are expected for the 2026-model-year changeover. Similar to several other 2026-model-year GMC vehicle lines, White Frost Tricoat (paint code G1W) paint will likely be replaced by Glacier White Tricoat (paint code G4J). Thunderstorm Gray (paint code GNO) is also expected to be replaced with the model year changeover.
Beyond that, the rest of the Sierra HD line will likely carry over unchanged. Engine options will once again include the 6.6L L8T V8 gasoline engine, rated at 401 horsepower at 5,200 rpm and 464 pound-feet of torque at 4,000. The 6.6 L5P V8 turbodiesel Duramax engine will be optional, rated at 470 horsepower at 2,800 rpm and 975 pound-feet of torque at 1,600 rpm. The Allison-branded 10-speed automatic transmission will be the exclusive transmission option. Both rear-wheel drive and four-wheel drive will be offered to put the power down.
The 2026 GMC Sierra HD will also continue to ride on a heavy-duty version of the GM T1 platform. Production will once again take place at the GM Flint plant in Michigan.
Looking ahead, the 2027 model year is expected to debut a brand-new generation for the light-duty GMC Sierra 1500. However, the current generation for the heavy-duty GMC Sierra HD is expected to soldier on until at least the 2027 model year, with the 2028 Sierra HD currently the most likely candidate for the launch of the heavy-duty pickup’s new generation, similar to way in which the current-gen HD trucks launched for the 2020 model year following the launch of the current-gen 1500 models for the 2019 model year.
Comments
For some reason GM and Ford are offering fewer and fewer color choices. If GM offered some version of blue on the AT4X, I would already have one. Unfortunately they don’t and it doesn’t look like they will. Ford has that super dark blue (Antimatter) but I like the GMC better. Looks like I may have to order a Super Duty Tremor in Antimatter Blue after all
Will the transmission be fixed 🤷