2026 GMC Sierra 3500 HD AT4 vs. 2026 Ram 3500 HD Big Horn in Squamish, BC
2026 GMC Sierra 3500 HD AT4 vs. 2026 Ram 3500 HD Big Horn at Greg Gardner Motors
Unlike the GMC Sierra 1500 and Ram 1500, the 2026 GMC Sierra 3500 and 2026 Ram 3500 sit in one of the most capable heavy-duty pickup truck segments, built for drivers who need extraordinary towing strength, durability, and confidence on the job or the road. Better yet, when you step up into higher trims, GMC offers the 2026 Sierra 3500 AT4, while Ram brings the 2026 3500 HD Big Horn, each designed to take capability even further. That naturally leads to the question: which one performs better? On paper, the specs are quite similar, but as you’ll see in this comparison, the 2026 Sierra 3500 AT4 brings more capability focused features, including advanced off-road hardware, smarter trailering technology, as well as driver-assist tools. Continue reading with our team at Greg Gardner Motors to see how they compare in detail.
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Engine Specs & Their Towing Capabilities
Starting with the 2026 Sierra 3500 HD AT4, the base engine is a 6.6L V8 gas engine producing 401 horsepower and 464 lb-ft of torque. If you step up to diesel, you get the legendary 6.6L Duramax Turbo-Diesel V8, which is capable of delivering an impressive 470 horsepower and 975 lb-ft of torque, built for heavy-duty hauling with confidence.
The 2026 Ram 3500 Big Horn comes with a 6.4L HEMI VVT V8 gas engine, producing 405 horsepower and 429 lb-ft of torque, which gives it a slight edge in horsepower on the gas side. For diesel power, it offers the 6.7L Cummins Turbo Diesel I6, producing 430 horsepower and a massive 1,075 lb-ft of torque, compared to the Sierra’s 470 horsepower.
When properly equipped with the diesel engines, both trucks reach a maximum towing capacity of up to 36,000 lbs (16,330 kg), meaning they are closely matched when it comes to ultimate pulling power.
| 2026 GMC Sierra 3500 HD | 2026 Ram 3500 HD | |||
| Engine Types | 6.6L V8 Gas | 6.6L Duramax Turbo-Diesel V8 | 6.4L HEMI V8 Gas | 6.7L Cummins Diesel I6 |
| Horsepower | 401 | 470 | 405 | 430 |
| Torque (lb-ft) | 464 | 975 | 429 | 1,075 |
| Max Towing Capacity (lbs) | 36,000 | 36,000 | ||
Off-Roading Features
This is where the 2026 GMC Sierra 3500 HD AT4 starts to separate itself, especially if you’re the kind of driver who takes the truck off pavement or works in tougher terrain.
The AT4 comes ready with a purpose-built off-road setup, including an off-road suspension with twin-tube Rancho shocks, skid plates for added underbody protection, and Hill Descent Control, which uses the anti-lock braking system to help you stay in control on steep declines. Inside the cabin, you also get a 15-inch diagonal head-up display with an off-road inclinometer, so you can monitor pitch and roll angles without taking your eyes off the trail. And when it’s time for trailering, the Sierra comes with up to 14 available camera views, including a transparent trailer view to help you see what’s behind the trailer as if it’s not even there. As well, the ProGrade Trailering Tech system helps streamline the entire hitching and towing process, making everything feel more controlled.
The 2026 Ram 3500 Big Horn, on the other hand, takes a more traditional “brute force” approach. It offers capable off-road and towing features as well, including available auto-level rear air suspension and Trailer Reverse Steering Control, which helps with backing up trailers more precisely. However, many of Ram’s more advanced off-road and towing technologies require additional upgrades or option packages, which can quickly increase the overall cost depending on how you configure the truck.
2026 GMC 3500 HD AT4 vs. 2026 Ram 3500 HD Big Horn Verdict
At the end of the day, the 2026 GMC Sierra 3500 HD AT4 and the 2026 Ram 3500 HD Big Horn are two workhorses built to tow up to 36,000 lbs when properly equipped with diesel powertrains. So, if you need power and torque for work or towing, you’re in great shape either way. That said, the GMC 3500 AT4 is the clear winner when you look beyond raw numbers and focus on how the truck performs in the places that matter most, with a host of innovative features that make no task too challenging.
Shop the 2026 GMC 3500 AT4 at Greg Gardner Motors in Squamish, BC
If you’re in Squamish or the surrounding area, the best way to experience it is in person at Greg Gardner Motors. This is where you can see the 2026 GMC 3500 AT4 up close, compare trims, and get a feel for how it performs when it’s loaded, towing, or tackling tougher terrain. Get in touch with one of our GMC specialists to have your questions answered. Better yet, fill out our online form to book your test drive, today.