2026 GMC Sierra HD

Sierra 2500HD: up to 22,390 lbs gooseneck/fifth-wheel towing (Regular Cab; 21,870 lbs Crew Cab) and up to 20,000 lbs conventional towing when properly equipped with the 6.6L Duramax and Max Trailering Package. Sierra 3500HD: up to 36,000 lbs gooseneck or fifth-wheel towing when equipped with the Duramax, Crew Cab, 4WD, and Max Trailering Package. Both models pair with the Allison 10-speed automatic transmission, engineered for grade-hauling and heavy-duty work-truck duty cycles. Maximum payload on the 2500HD reaches 4,478 lbs.

Choose 2500HD for gooseneck/fifth-wheel towing up to 22,390 lbs (20,000 lbs conventional), maximum payload of 4,478 lbs, and single rear wheels (SRW). Choose 3500HD for gooseneck/fifth-wheel towing up to 36,000 lbs, available dual rear wheels (DRW) for higher load capacity, and the extra capability of a true heavy-duty platform. Both come in Pro through Denali Ultimate trims with the same engine options. The 3500HD has no AT4X — the AT4X is exclusively a 2500HD trim.

Two powertrains, both paired with the Allison 10-speed automatic transmission: (1) 6.6L V8 gas delivering 401 HP and 464 lb-ft of torque, the standard engine on every trim except Denali Ultimate; (2) 6.6L Duramax turbo-diesel V8 delivering 470 HP and 975 lb-ft with peak torque at 1,500 RPM, standard on Denali Ultimate and available on every other trim, including Denali. The Duramax is engineered for grade-hauling and immediate pulling power.

Sierra 2500HD: up to 4,478 lbs payload, with gmc.com Build & Price cab/box ranges running 3,612-4,478 lbs. Sierra 3500HD payload depends heavily on single- vs dual-rear-wheel setup and body configuration. Payload varies by engine, driveline (2WD vs 4WD), bed length, and configuration. Call Marty's GMC at (781) 936-0081 to confirm the exact payload capacity for a specific trim and configuration.

Yes. Super Cruise hands-free driving is available on Denali and Denali Ultimate trims. It works on over 600,000 miles of compatible roads in the U.S. and Canada, including I-93, I-95, and Route 3 around the South Shore. Three years of Super Cruise service are included with eligible new vehicles. Driver attention is monitored continuously by an IR camera.

The MultiPro Tailgate is GMC's signature six-function tailgate with positions including Primary Gate, Primary Gate with Load Stop, Inner Gate Load Stop, Full-Width Step (375-lb grab handle), Easy-Access Setup, and Work Surface. Standard on SLT and above. Pro and SLE trims receive a standard power tailgate. An available MultiPro Audio System by Kicker turns the tailgate into a powered speaker.

SRW (Single Rear Wheel) is the standard configuration on Sierra 3500HD, with a single wheel on each side of the rear axle. DRW (Dual Rear Wheels) is available and adds a second rear wheel on each side, increasing load capacity, improving stability during heavy gooseneck or fifth-wheel towing, and maximizing payload. Required for maximum 36,000 lbs gooseneck towing.

Every 2026 Sierra HD with the 6.6L Duramax includes a 5-year/100,000-mile diesel powertrain warranty, plus a 5-year/100,000-mile roadside assistance and courtesy transportation program. Gas-engine vehicles include a 5-year/60,000-mile powertrain warranty. All models include a 3-year/36,000-mile bumper-to-bumper limited warranty. Marty's GMC service uses ASE-certified technicians and full GMC diagnostic equipment.

For September 2026: 4.9% APR for 48 months on 2026 Sierra 2500HD and 3500HD Denali financed through GM Financial, plus a $2,000 Purchase Allowance, plus no monthly payments until next year (payments deferred 122 days; finance charges accrue from the date of financing; excludes PA residents). New this month: a $3,500 Purchase Allowance on Sierra HD Denali with the Duramax diesel (diesel engines only). The 2500HD Denali also has a featured national lease at $799/month for 36 months with $8,229 due at signing. All programs require new retail delivery by September 30, 2026. Call (781) 936-0081 for full eligibility.

No. The AT4X is a 2500HD-exclusive trim. The 3500HD lineup consists of Pro, SLE, SLT, AT4, Denali, and Denali Ultimate. Both the 2500HD and 3500HD offer factory off-road AT4 capability with lifted suspension, all-terrain tires, skid plates, and hill descent control.

Browse 2026 Sierra 2500HD inventory and 2026 Sierra 3500HD inventory at martysgmc.com/searchnew.aspx, or call (781) 936-0081 to speak with a truck specialist or schedule a test drive. Open Mon–Thu until 7 PM, Fri until 6 PM, Sat until 4 PM.