2021 GMC Sierra 3500HD Trim Levels with Comparisons & Configurations.

The 2021 GMC Sierra 3500HD is a powerhouse of versatility, excelling both on and off the road. This heavy-duty truck offers an optimal payload capacity for tough working conditions with its Regular, Double or Crew Cab body styles – plus four robust 4X4 variations to conquer any terrain! A powerful V8 diesel engine ensures performance under pressure while sleek exterior styling makes it attractive enough to serve as your daily driver too. With five different trim levels available along with numerous configurations and even one special edition model - this vehicle has something for everyone looking for some serious muscle in their new ride.

Compare the 3500HD Base vs SLE. What Is the Difference?

Climb up behind the wheel of a Base trim level in either Regular, Double or Crew Cab configurations. Those opting for a two-door setup can select from single rear wheels to double their payload capacity; those choosing four full doors will benefit from plenty of room for backseat passengers. Underneath it all is tucked away an impressive 6.6-liter V8 gasoline engine with direct injection and variable valve timing - producing 401 horsepower and 464 pound-feet of torque! Transferring power to the 2WD/4WD options you also get a six speed automatic transmission as standard on this capable powerhouse truck bed set up that offers so much more than just versatility.

Take your GMC Base to the next level with an upgrade engine and transmission! The 6.6-liter Turbo Diesel has a 10-speed Allison automatic for unbeatable power, enabling you to carry up 4185 pounds or tow 36000 when outfitted with dual rear wheels. Add some rugged style outside: LED headlights, 18" alloy wheels fitted with all terrain tires make this truck stand apart from others on the road while chrome grille & bumpers give it true street presence& EZ Lift tailgate gives quick access in any payload situation - plus you've got 12 cargo tie downs too! Solar absorbing glass helps keep it cool whatever job you choose inside.

With the Base model, you get a comprehensive interior package complete with four-way manual seats in an innovative 40/20/40 split bench setup. A 7-inch touchscreen and six speakers offer up entertainment features plus ease of use; power windows and locks come as standard too. Practicality abounds across easy to clean vinyl seating surfaces, bolstered by rubberized flooring for extra durability - all regulated via Single Zone Climate Control! And on top of that comes enhanced peace of mind courtesy Sound Security with six airbags, Rear Vision Camera and Tire Pressure Monitoring System.

GMC has a system called Teen Driver. Every trim level of the 2021 GMC Sierra 3500HD gets this technology. It allows the truck owner to set parameters for younger, second drivers. It also gives you a report card to let you know how the driver is doing. All trims also have StabiliTrak which provides stability and traction control.

The SLE trim is the perfect upgrade for those looking to add a bit of style, comfort and convenience to their car. It offers all the same body styles and configurations as its Base model, plus some impressive new features like 18-inch aluminum wheels with glossy black accents that will turn heads wherever you go. Inside changes including steel colored belt line moldings give it an extra touch of sophistication while deep tinted windows provide added privacy on your drives anywhere you choose. Don't forget about Lower Assist tailgate too – making loading up cargo more efficient than ever before.

Moving on to the inside, the SLE gets a bigger driver-info display in the instrument cluster. The infotainment system gets some upgrades too. You can get a larger 8-inch touchscreen along with 4G WiFi Hotspot capability. GMC Connected Access and OnStar are available for this model. The steering wheel comes wrapped in leather at this trim level.

The rear area now gets rubberized vinyl floor mats. The upholstery is upgraded to fine cloth. Audio-system controls now come mounted on the steering wheel for easy, safer access. You also get some extra USB ports at this trim level for charging up your phones and other devices. The SLE also offers Keyless Entry.

The standard safety features are no different than the base model. There are some new optional add-ons though. There's an available Bed-View Camera so you can keep an eye on your cargo. The regular Rear-Vision Camera can be upgraded to high definition. You can get a Hitch Guidance with Hitch View and a Tire-Pressure Monitor for your trailer tires.

Compare the 3500HD SLE vs SLT. What Is the Difference?

Put the power in your hands with GMC's SLT trim. Offered exclusively as a Crew Cab, you can choose between standard or long bed length and two-wheel drive or four-wheel drive variations - single rear wheels optional, too! Boasting V8 gasoline engine stock (diesel still available), this model also features MultiPro Tailgate for easier loading/unloading accompanied by powerful lock & release mechanism plus additional lighting to boot.

And that’s not all; 4WD vehicles get 2 speed transfer case w/ push button controls alongside Digital Variable Steering Assist technology – optimizing steering dynamics depending on driving conditions – while those opting for SLE can add an optional Trailering Package and Prograde Trail Scoring Package when going full out SLT style.

For the exterior, both models feature the same 18-inch aluminum wheels. These have a 6-spoke design and glossy-black accents. The cargo bed gets some addition LED lights on the SLT trim. On the inside of the SLT, the seats are upgraded to models with 10-way power adjustments and lumbar support.

The front bench seat gets an extra storage compartment underneath of it for this trim. There is now dual-zone climate control. The front seats now offer a heating feature. The safety features remain mostly the same. The Rear-View Camera gets upgraded to an HD model. Lane Departure Warning is optional for the first time at this trim level.

Compare the SLT vs AT4. What Is the Difference?

The AT4 trim level was built for optimal off-road performance. As such, it can only be purchased with 4X4 four-wheel drive. It is only available in the Crew Cab, but you can choose either a regular or long cargo bed. The AT4 is not available in a dual rear-wheel setup.

The main draw for the AT4 is the X31 Off-Road Package. This includes an upgraded off-road suspension, twin-tube Rancho shocks, skid plates and Hill Descent Control. There are also X31 Off-Road badges on the exterior to show off your truck's off-road capabilities. All of the safety features from the SLT trim make a return here.

On the inside, the AT4 gets all-weather floor liners with the AT4 logo. You get the top-tier infotainment system with Bluetooth connectivity and a WiFi Hotspot. There are extra USB ports here for even more charging stations and connectivity options. In addition to the front seats, the rear seats also now have the heating feature.

Compare the 3500HD AT4 vs Denali Trims. What Is the Difference?

The AT4 is the off-road king of the 2021 GMC Sierra 3500HD lineup. The Denali is the luxury model of the bunch. It still offers the same amazing performance with the ability to tow or haul massive loads. This model, however, was also crafted with comfort and convenience in mind. It's an excellent vehicle for daily commutes and family hauling.

The Denali is only available in the four-door Crew Cab variation, as should be expected for a luxury truck. You can get a regular or extended cargo bed if needed. You can also get a Denali with the dual rear wheels if you should need the extra hauling capacity.

The AT4 and Denali both come equipped with the gasoline-powered V8. The Diesel engine is optional for both. Two nice additions to the Denali are the Driver Alert Packages. There are two of them added on here. This includes features such as Lane Change Alert with Side Blind Zone Alert and Rear Cross Traffic Alert.

Perimeter lighting is added at this level. You also get Front and Rear Park Assist. Forward Collision Alert, Automatic Emergency Braking and a Following Distance Indicator are all included here. For the exterior, the Denali gets plenty of chrome trim on the door handles, the grille and more.

The infotainment system for the Denali gets a navigation system to help you find your destination. The audio system gets upgraded to a Premium Bose Package with seven speakers and a Richbass woofer. An included Home Remote gives the driver access to garage doors and home security systems.

3500HD Special Editions

In addition to the standard trim levels, there is also a special edition of the 3500HD Denali for 2021. This model is called the Denali Black Diamond Edition. This model comes in a single rear-wheel configuration with four-wheel drive. It comes equipped with a 6.6-liter Turbo-Diesel V8 and a 10-speed automatic transmission.

This special edition comes in a unique paint color that GMC calls Ebony Twilight Metallic. It has a blacked-out motif with a darkened grille, bumpers and exterior mirrors. The 20-inch aluminum wheels come in a special glossy-black paint scheme as well. Other than the cosmetic flourishes, this model is largely the same as a standard 3500HD Denali.

Some highlights here include a power sunroof, power-retractable steps and exterior lighting via some powerful LEDs. All-weather floor liners and removable carpets make cleaning out the truck a breeze. Also included is a premium audio system from KICKER.

Final Thoughts

The 2021 GMC Sierra 3500HD offers many options for drivers looking to tailor their truck to specific needs. Decisions such as 4X2 or 4X4 models, Crew Cab or Regular Cab sizes and Denali, AT4, SLT trims will help match you with the perfect vehicle thanks to varying capabilities in handling rough terrain and hauling loads. With a Base trim that keeps it simple but powerful or an all-inclusive Denali model - this workhorse has something perfectly suited for everyone's budget! For those who need extra off-road power there is always the capable AT4 version which provides excellent performance at just a modest price increase from other levels of luxury and convenience offered by the midlevel SLE & SLT packages too.