“About the features, heads up display, mirrors, heated/cooled seats, steering wheel warmer”
2021 GMC Sierra 3500: What's New, Specs & Features
Last updated August 13, 2026
The 2021 GMC Sierra 3500 HD is a light update rather than a redesign. Its biggest change is a higher maximum tow rating of 36,000 pounds with the proper diesel dually and gooseneck setup.
About the 2021 GMC Sierra 3500
4th-generation Sierra HD, second model year after the 2020 redesign.
GMC positions the Sierra 3500 HD as a heavy-duty truck that can handle serious towing and hauling without feeling stripped down unless you want it that way. Across the range, the pitch is professional-grade capability, smarter trailering tools, and more premium design than a purely work-first HD pickup. Compared with its Chevrolet sibling, the Sierra leans harder into upscale styling, the MultiPro tailgate, and personality trims like AT4 and Denali.
The lineup runs from a vinyl-floor base work truck with a 6.6-liter gas V8 to the off-road-focused AT4 and luxury-focused Denali. AT4 has standard 4WD, Rancho shocks and skid plates, while Denali pairs leather seating with surround-view and bed-view cameras.
What changed, by category
Structural
The maximum tow rating increases to 36,000 pounds with the proper diesel dually and gooseneck configuration. The MultiPro tailgate becomes standard on SLE, SLT, AT4 and Denali.
Tech
Upper trims gain wireless Apple CarPlay and Android Auto. Denali gains standard HD Surround Vision and a bed-view camera.
2021 GMC Sierra 3500 specs and features by trim
| Feature | |||||
|---|---|---|---|---|---|
| Engine | V8, 6.6 Liter / V8, Turbo Diesel, 6.6 Liter | V8, 6.6 Liter / V8, Turbo Diesel, 6.6 Liter | V8, 6.6 Liter / V8, Turbo Diesel, 6.6 Liter | V8, 6.6 Liter / V8, Turbo Diesel, 6.6 Liter | V8, 6.6 Liter / V8, Turbo Diesel, 6.6 Liter |
| Transmission | Automatic, 6-Spd HD w/Overdrive | Automatic, 10-Spd Allison | Automatic, 10-Spd Allison | Automatic, 6-Spd HD w/Overdrive | Automatic, 6-Spd HD w/Overdrive |
| Drivetrain | 4WD | 4WD | 4WD | 4WD | 4WD |
| Fuel Type | Gas / Diesel | Gas / Diesel | Gas / Diesel | Gas / Diesel | Gas / Diesel |
| Horsepower | 401–445 hp | 401–445 hp | 401–445 hp | 401–445 hp | 401–445 hp |
| Torque | 464–910 lb-ft | 464–910 lb-ft | 464–910 lb-ft | 464–910 lb-ft | 464–910 lb-ft |
| Max Towing | 14500 lb | 14500–16300 lb | 14500–16300 lb | 14500–16300 lb | 14500 lb |
| Rear Legroom | 43.4 in | 35.2–43.4 in | 43.4 in | 35.2–43.4 in | 43.4 in |
| Seats | 3–6 | 6 | 3–6 | 5 | |
| Doors | 4 | 2–4 | 4 | 2–4 | 4 |
| Alarm System | |||||
| Automatic Emergency Braking | |||||
| Automatic High Beams | |||||
| Blindspot Sensors | |||||
| Cruise Control | |||||
| Hill Descent Control | |||||
| Lane Departure Warning | |||||
| Park Assist | |||||
| Rear View Camera | |||||
| 360 Camera | |||||
| Alloy Wheels | |||||
| Fog Lights | |||||
| HID Headlights | |||||
| Heated Mirrors | |||||
| LED Headlights | |||||
| Memory Exterior Mirrors | |||||
| Power Moonroof | |||||
| Power Mirrors | |||||
| Power Side Steps | |||||
| Privacy Glass | |||||
| Side Steps | |||||
| Tow Hooks | |||||
| Head-Up Display | |||||
| Navigation System | |||||
| Premium Audio | |||||
| SD Card Slot | |||||
| Satellite Radio | |||||
| Smartphone Interface | |||||
| Subwoofer | |||||
| Touch Screen Monitor | |||||
| Auto-Dimming Interior Mirror | |||||
| Dual Power Front Seats | |||||
| Dual-Zone Climate Control | |||||
| Heated Front Seats | |||||
| Heated Rear Seats | |||||
| Heated Steering Wheel | |||||
| Integrated Garage Door Opener | |||||
| Leather Seats | |||||
| Leather-Wrapped Steering Wheel | |||||
| Memory Driver's Seat | |||||
| Power Adjustable Pedals | |||||
| Power Driver Seat | |||||
| Remote Start | |||||
| Remote Keyless Entry | |||||
| Tilt Wheel | |||||
| Tilt/Telescoping Steering Wheel | |||||
| Ventilated Front Seats | |||||
Frequently asked questions
What is the biggest change to the 2021 GMC Sierra 3500 HD?
The biggest change is a higher maximum tow rating. A properly configured 2021 Sierra 3500 HD diesel dually with a gooseneck setup is rated to tow up to 36,000 pounds.
Is the 2021 GMC Sierra 3500 HD a redesign?
No. The 2021 Sierra 3500 HD is a light update in the second model year following the 2020 redesign.
Which 2021 GMC Sierra 3500 HD trims have the MultiPro tailgate as standard equipment?
The MultiPro tailgate is standard on the 2021 Sierra 3500 HD SLE, SLT, AT4 and Denali trims. The work-focused base trim is not included in that group.
Does the 2021 GMC Sierra 3500 HD have wireless Apple CarPlay and Android Auto?
Yes, upper 2021 Sierra 3500 HD trims have wireless Apple CarPlay and Android Auto. The feature is part of the upgraded touchscreen setups in trims including SLT, AT4 and Denali.
What changed on the 2021 GMC Sierra 3500 HD Denali?
The 2021 Sierra 3500 HD Denali gains standard HD Surround Vision and a bed-view camera. These systems give the driver more views around the truck and into the cargo bed while maneuvering or towing.
2021 GMC Sierra 3500 Reviews
What owners are saying about the 2021 GMC Sierra 3500.
4.3
2021 GMC Sierra 3500
(83 reviews)
“10-speed [Name] transmission is excellent. Extended wheelbase is unexpected and takes getting used to.”
“The tires are out of balance and two different GMC dealers can't seem to fix it or agree upon what type of testing should be done. Both using the excuse that GM only allows them to do "so much". VERY frustrating.”