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The 2027 GMC Sierra HD introduces a new available Duramax 8.3L Turbo-Diesel V8 producing 1,230 lb-ft of torque. That torque figure pushes maximum available towing to 38,000 lbs, a significant jump over the 2026 model’s 36,000-lb ceiling. This page covers every trim, powertrain detail, and new feature, along with upcoming 2027 Sierra HD availability at Greg Hubler Buick GMC in Marion, IN.
The 2027 Sierra HD is a ground-up advancement over the outgoing model. The headline addition is the all-new Duramax 8.3L Turbo-Diesel V8, which delivers 555 hp and 1,230 lb-ft of torque. Those are class-leading figures for diesel horsepower and torque in this segment. GMC Sierra HD capability claims
Two segment-first technologies also debut on this truck. The first is electric rack-and-pinion power steering, which GMC says creates a more precise, responsive feel compared to the hydraulic systems found on competing HD trucks. The second is the eBoost electronic brake boost system, designed to provide firm brake response on downhill grades and reduce trailering stopping distances. Both are firsts in the heavy-duty pickup segment.
The AT4X trim also gains Terrain Mode for the first time on Sierra HD. Terrain Mode adjusts shift mapping and traction control, and it adds automatic braking for low-speed maneuvering on uneven surfaces.
The 2027 Sierra HD is expected to arrive in late 2026. Preproduction models are shown throughout this page, and actual production models may vary.
The 2027 Sierra HD spans seven trims. Each builds meaningfully on the one below it.
Pro is the entry point and arrives with more standard capability than many HD competitors offer at this level. It includes the 6.6L V8 gas engine with the Allison 10-speed automatic transmission, Adaptive Cruise Control with trailering capability, a Trailer Brake Controller, Trailering Package, and Trailering Mirrors.
SLE adds the 13.4-inch Premium GMC Infotainment System, a 12.3-inch digital Driver Information Center, the Traction Select System with Tow/Haul mode, and 18-inch machined aluminum wheels.
SLT steps up to available 10-way power-adjustable, heated and ventilated front bucket seats with perforated leather appointments, a heated steering wheel, and the ProGrade Trailering System with the In-Vehicle Trailering App.
AT4 targets buyers who want off-road capability without giving up daily comfort. It brings an exclusive Jet Black interior with Kalahari accents, heated and ventilated perforated front leather seating, exclusive 20-inch Gloss Black aluminum wheels, an available BFGoodrich All-Terrain tire option, and an Off-Road Suspension Package with twin-tube shocks and skid plates.
AT4X is the serious off-road configuration. It adds a factory-installed 1.5-inch suspension lift, Multimatic DSSV dampers, a rear electronic-locking differential, a larger steel transfer case skid plate, a front aluminum skid plate, 35-inch Goodyear Territory MT tires, 16-way heated and ventilated power front seats with a massage feature, and the debut of Terrain Mode on Sierra HD.
Denali pivots to premium comfort. It includes 20-inch Ultra-Bright machined aluminum wheels with bright chrome inserts, Denali-exclusive authentic wood trim, patterned aluminum trim, Forge perforated leather seating surfaces, and 12-way heated and ventilated power front seats.
Denali Ultimate is the flagship. It is the trim that pairs the new Duramax 8.3L Turbo-Diesel V8 with the Allison 10-speed automatic as standard equipment. It also includes a Signature Vader Chrome grille, exclusive 20-inch Ultra-Bright machined aluminum wheels with Gloss Black inserts, and an exclusive Alpine Umber interior with full-grain leather seating, authentic Paldao wood trim, and 16-way power front seats with a massage feature.
Two engines are available for the 2027 Sierra HD.
The standard engine is an enhanced 6.6L V8 gasoline unit paired with the Allison 10-speed automatic transmission. GMC describes this as an improved version of the outgoing engine.
The available engine is the all-new Duramax 8.3L Turbo-Diesel V8. It produces 555 hp and 1,230 lb-ft of torque, both class-leading figures for the HD diesel segment. This engine also pairs with the Allison 10-speed automatic.
Maximum available towing reaches 38,000 lbs on properly equipped 3500 models with the Duramax diesel. The 2500 configuration achieves a maximum available towing capacity of 23,100 lbs.
Segment-first electric rack-and-pinion power steering is standard across the lineup, replacing the hydraulic systems used on competing HD trucks. The eBoost electronic brake boost system, also a segment-first, works with large front brakes to improve brake response under load and during downhill towing.
The 2027 Sierra HD seats six passengers. Across the trim lineup, seating quality escalates from durable work-truck material on the Pro to full-grain leather on the Denali Ultimate.
Available features include 16-way power front seats with a massage function, found on the AT4X and Denali Ultimate trims. Heated and ventilated front seats are available from the SLT upward. The Denali Ultimate’s Alpine Umber interior uses authentic Paldao wood trim and topographic-pattern stitching on the leather seating surfaces.
The AT4 and AT4X carry exclusive interior color schemes that differentiate them visually from the luxury-oriented Denali trims.
The available 13.4-inch Premium GMC Infotainment System anchors the Sierra HD’s digital cabin, first appearing on the SLE trim. It is joined by an available 12.3-inch digital Driver Information Center and an available 15-inch multicolor Head-Up Display, which puts key driving and trailering data at eye level.
Audio is handled by an available 12-speaker Bose Premium Series audio system.
The ProGrade Trailering System, available on SLT trims and above, includes an In-Vehicle Trailering App. GMC offers up to 14 available camera views to assist with hitching, maneuvering, and monitoring trailers while underway.
Adaptive Cruise Control with trailering capability is standard from the Pro trim, meaning the radar-based system accounts for the added weight and length of a trailer when managing following distance.
The eBoost electronic brake boost system is a segment-first feature standard on the 2027 Sierra HD. It uses large front brakes and improved braking mechanics to deliver a firm pedal feel during downhill grades and to reduce trailering stopping distances.
Adaptive Cruise Control with trailering capability is standard on the base Pro trim, giving buyers the full suite from the entry level upward.
A Trailer Brake Controller is also standard on the Pro, eliminating the need to add an aftermarket unit for most trailering setups.
The Traction Select System with Tow/Haul mode, available on SLE and above, helps the transmission manage shift points and engine braking when hauling heavy loads. The AT4X adds Terrain Mode, which builds on this foundation with automatic low-speed braking for technical off-road situations.
The 2027 Sierra HD is the right truck for buyers who regularly pull heavy loads, whether that means a fifth-wheel RV, a commercial equipment trailer, or a livestock hauler. The 38,000-lb towing capacity, available Duramax diesel, and segment-first braking and steering upgrades represent a meaningful capability leap over the 2026 Sierra HD.
The 2026 Sierra HD remains a capable truck, with up to 36,000 lbs of available towing and the proven 6.6L V8 gas and diesel powertrains. Buyers who need maximum capability and want the latest technology in segment-first steering and braking will find the 2027 model to be a substantive upgrade rather than a refresh.
For buyers in Marion and across Indiana who do serious commercial or recreational trailering, the 2027 Sierra HD’s numbers set a new benchmark.
The 2027 GMC Sierra HD has not arrived at Greg Hubler Buick GMC yet and is expected to arrive in late 2026. Shoppers interested in the upcoming model can contact the dealership for release updates, availability information, and help determining which Sierra HD configuration fits their towing and hauling needs.
In the meantime, shoppers can browse current Sierra HD inventory, value a trade, or speak with the Greg Hubler Buick GMC team about the upcoming 2027 lineup.
The 2027 GMC Sierra HD is expected to arrive in late 2026. Contact Greg Hubler Buick GMC in Marion for release updates and upcoming availability information.
The 2027 Sierra HD 3500 tows up to 38,000 lbs when properly equipped with the available Duramax 8.3L Turbo-Diesel V8. The 2500 configuration reaches a maximum available towing capacity of 23,100 lbs.
The 2027 Sierra HD adds an all-new available Duramax 8.3L Turbo-Diesel V8 producing 555 hp and 1,230 lb-ft of torque, paired with an Allison 10-speed automatic transmission. The standard engine remains an enhanced 6.6L V8 gasoline unit.
eBoost is GMC’s electronic brake boost system, a segment-first feature on the 2027 Sierra HD. It uses large front brakes and improved braking mechanics to deliver firm pedal response on downhill grades and to help reduce stopping distances when trailering.
The 2027 Sierra HD uses rack-and-pinion electric power steering, replacing the hydraulic setups found on competing heavy-duty trucks. GMC says this system produces a more precise and responsive steering feel, particularly during towing maneuvers.
The 2027 Sierra HD is offered in seven trims: Pro, SLE, SLT, AT4, AT4X, Denali, and Denali Ultimate. The Denali Ultimate is the flagship and includes the Duramax 8.3L diesel as standard equipment.
Terrain Mode makes its Sierra HD debut on the 2027 AT4X trim. It adjusts shift mapping and traction control settings, and adds automatic braking to improve control during low-speed maneuvers on uneven off-road surfaces.
The ProGrade Trailering System with the In-Vehicle Trailering App is available on SLT trims and above. It works with up to 14 available camera views and Adaptive Cruise Control with trailering capability to create a connected towing experience.