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2020 GMC Sierra 3500HD Trim Levels with Comparisons & Configurations.

2020 GMC Sierra 3500HD Trim Levels, Configurations & Comparisons: Base vs SLE vs SLT, AT4 & Denali
Reviewed & fact checked by
James Murdoch

What 2020 GMC Sierra 3500HD Trim Level Should you Buy? What is the Difference Between Trims?

The GMC Sierra 3500HD is built for hard work. Five trims give customers plenty of options, especially when there are different cabs and beds to choose from. All-wheel drive is available, as is a diesel engine. A major advantage to the 3500HD is that potential GMC Sierra drivers can customize their trucks to their liking.

Dimensions on this GMC pickup are generous. The long bed measures 98.27 inches, and it can be paired with the regular, double, and crew cabs. The standard bed is noticeably shorter, but still sizable, at 82.25 inches. It's matched with either the double or crew cab. The regular cab only has one row of seating, and the double cab has a second row with 35 inches of leg room compared to the 43 inches in the crew cab.

There are two engines that can power up the truck. The standard is a 6.6-liter V8 model with variable valve timing. It's matched with a six-speed heavy-duty transmission that has automatic shifting.

The other choice is a 6.6-liter Duramax V8. This is a turbo-diesel that comes with 445 horsepower and 910 pound-feet of torque; this is a major increase over the gas-powered engine's 401 horsepower and 464 pound-feet of torque. The Duramax feels smooth and powerful at all speeds, thanks to a ten-speed Allison automatic transmission. There's the opportunity to get that automatic transmission with an integrated Power Take Off if it would be appropriate given's one work or hobbies.

How does all of this translate to towing capacity? Statistics vary according to the type of truck chosen since the weight of the actual truck and its configuration can affect capacities. Here are a few examples to give a better idea of what these trucks can handle:

  • A crew cab with a standard bed and the gas engine can tow up to 14,500 pounds and has a maximum payload of 4,316 pounds. When equipped for 5th wheel trailering, it can tow up to 16,700 pounds.
  • A regular cab with a long bed and the Duramax engine has a trailering capacity of 20,000 given a traditional set-up. When 5th wheel trailering is factored into play, capacity increases to 31,700 pounds.

Since there is so much to think about when buying a new 2020 GMC Sierra 3500HD, it can be wise to go over all the information in detail before making a decision. Here is a guide that compares the trims on the GMC truck.

Compare the 2020 GMC Sierra 3500HD Sierra vs SLE Trim Levels. What is the difference?

The entry model, which is called the Sierra, has a relatively modest interior and has some basic features on the exterior. It has 18-inch wheels like the SLE does, but they differ slightly in aesthetics. The Sierra has painted silver wheels with eight spokes, and the SLE has six-spoke machined aluminum wheels that are highlighted with some glossy black accents.

Both trims have a standard tailgate with the option to upgrade to one with a power lock and release, but the SLE comes with an assist system - called EZ lift - that makes it easier to open and close. LED headlamps and taillamps are standard, as are LED daytime running lamps. In the bed, there are lamps and available LED lighting to help people see what they're doing, and tie downs can often come in handy to keep cargo from sliding around.

Chrome bumpers act as nice accents on either side of the truck, and the SLE has vertical trailering mirrors that can be very useful in improving line of sight. Neither trim is built with assist steps, but they are an available option, with the SLE coming with the choice of four different types of assist steps.

Inside the cab, the two trims have some more differences. The base Sierra model only has two speakers, while the SLE has six. The 40/20/40 split-bench in the front is fairly spartan in the Sierra, with the driver's seat having manual adjustments. In the SLE, the front bench comes with a covered armrest that has storage. Its driver's seat is manually adjustable, and there is the option to upgrade to a 10-way power seat.

Seats on the Sierra are trimmed in vinyl, which is easy-to-clean. This compares with the cloth seat trim on the SLE. The SLE has a leather-wrapped steering wheel (with mounted audio controls) that feels soft and is easy to get a firm hold of. It can be upgraded to one that's heated if anyone wishes to warm things up even further in winter. Likewise, heated front seats are available on the SLE. If a driver prefers to have bucket seats in the front, they are available starting with the SLE trim.

It's important to note that the base Sierra trim will come with manual windows and power door locks unless one specifically choose to upgrade to power-operated ones. This is actually hard to find these days, and some consumers won't mind this low-tech element.

In terms of technology, the package isn't bad to start. Bluetooth is a standard feature, as is a color touchscreen on which the infotainment system is controlled. A seven-inch touchscreen is featured on the Sierra, and it's enhanced to an eight-inch model on the SLE. Apple CarPlay and Android Auto are included as well.

Only one USB port is included on the Sierra, whereas the other trims have multiple ports that are more convenient for modern drivers. Remote keyless entry, which ensures that keys can be safely stored, is standard on the SLE and available on the Sierra.

Having hitch guidance is an advantage with the Sierra. It displays guidelines through the rear vision camera feed to help drivers line up correctly with their trailers. Another function that drivers can rely on is a program called StabiliTrak, which works to enhance both stability and traction.

Compare the 2020 GMC Sierra 3500HD SLE vs SLT Trims. What is the difference?

When moving up to the SLT, there are some key changes. First of all, the SLT comes with a MultiPro Tailgate. It has a versatile design that allows for six different configurations. Power lock and release are automatically included, as is hitch area lighting that really comes in handy when it's dark outside. Also, a digital variable steering assist feature can make corrections to steering based on road conditions and speed to enhance safety.

The interior of the cab is much nicer on the SLT. Its standard features include 10-way power-operated seats for both the driver and passenger, 12-volt outlets in the front and in the back, and a 120-volt outlet that can provide juice for power tools and more. Plus, the driver's seat has memory so the primary driver can quickly find his or her favorite position after someone else has gotten behind the wheel. Dual-zone climate control can be appreciated if the two people have different preferences.

The infotainment system on the SLT is upgraded to have a multi-touch display, and it can play HD Radio and SiriusXM radio in addition to the regular AM/FM stations. Voice commands and select apps are supported as well, giving people much more ability to stay in touch with others, get the information they're looking for, and keep their hands on the wheel.

Outside the SLT, there are more similarities than differences when matching it up to the SLE. A few changes are that the SLT has chrome door handles instead of black ones, it has standard LED lighting in the cargo bed, and it has high-intensity headlamps and LED turn signals. Its vertical trailering mirrors have a clever power folding and extending function and can automatically dim if bright lights are detected.

Those who tow frequently may want to choose the SLT because it has the ProGrade Trailering System. This includes an advanced hitch guidance program that comes with hitch view. This program uses a camera that can zoom-in, pan, and tilt, and the parking brake can automatically be applied when going from Reverse to Park. It also includes a trailering app that can be used in the cab to keep track of how things are going while on the road.

Compare the 2020 GMC Sierra 3500HD SLT vs AT4 Trims. What is the difference?

At the AT4 level, drivers get to take advantage of an Autotrac two-speed transfer case. It gives people the option to choose between 2WD High, which would be ideal for most situations, or 4WD High or Low. The 4WD low setting would provide maximum torque, for when needed in situations like sand or mud. 4WD high would be used on snowy or wet roads that aren't too extreme. Since the system has an automatic feature, it can independently change settings for when more traction is needed.

Exterior details, such as door handles that match the body of the truck and black belt line moldings, give the Sierra AT4 a different style. The spray-on bedliner in the back provides the truck with a highly durable, non-skid surface. Since the bedliner is chemically bonded to the truck, everything is watertight and sure to last.

On the inside of the AT4, there is the same eight-inch touchscreen and infotainment system as the SLT has. Both trims come with the option to incorporate navigation into the system. For seating, the AT4 comes with front bucket seats and a center console that can be used for storage. Heated seats are found in the front and in the back, which is a nice perk for the extra passengers, and the front seats come with ventilation as well.

Up until this point, the trims have all had a similar safety package. For instance, parking assist and other driver-assist features have been optional or not available. At the AT4 level, the truck starts to come with hill descent control. This function alleviates the need to put constant pressure on the brakes while traveling downhill, as the truck can manage itself in a way that controls speed.

Compare the 2020 GMC Sierra 3500HD AT4 vs Denali Trim Levels. What is the difference?

The Denali stands out as a premier model in the GMC Sierra 3500HD family. It shows its prowess with its 20" wheels, which can be either chrome aluminum or high gloss black painted versions. It's the only trim that comes standard with six-inch chrome rectangular assist steps.

With the Denali, the door handles and mirror caps switch back to being finished in chrome. At the rear of the truck, there is a polished exhaust tip as well as a power rear window that has its own defogger. What's unique about the headlamps on this truck is that they can automatically switch between high and low beams, depending on what the sensors pick up from other vehicles or street lights. Another cool feature is the smoked amber LED lamps that are found on the roof.

An eight-inch touchscreen is built into the Denali, like it is on the AT4. However, the Denali's infotainment system has navigation. Also, the sound system is upgraded to one that has Bose speakers. Seven speakers are located throughout the cabin, and a Richbass woofer rounds out the sound. SiriusXM with 360L is an enhanced subscription package that the Denali supports, giving people more opportunities in terms of the information they have access to. Additionally, the Denali is the only trim that comes standard with wireless charging and the ability to send signals to residential garage doors and select security systems.

Safety is a category in which the Denali stands far apart from the rest of the 3500HD trucks. It has automatic emergency braking that can engage at speeds under 50 miles per hour, a following distance indicator, and an alert that will let people know if a forward collision seems imminent. It also has a parking assist feature that can make parallel parking and perpendicular parking less tricky. Blind zone monitoring and a system that keeps drivers centered in their lanes round out the safety package.

Which Trim to Choose?

Though their prices are attractive, the lower trims can feel a little underwhelming. This is especially the case with the base Sierra, which has vinyl seats and manual windows. At the other end of the spectrum, the Denali has numerous high-end features, like automatic headlamps and built-in navigation. At what point is the price balanced appropriately with the trim's features?

Most drivers will want to strongly consider getting the SLT. It has modern elements, like power-operated front seats and a multi-touch display, and it has a functional and convenient MultiPro Tailgate and ProGrade Trailering System.

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