Used 2021 GMC Sierra 3500HD for Sale nearChicago, IL

How much does the 2021 GMC Sierra 3500HD cost?

Prices have softened 7.29% compared to this time last year, making it a favorable time to shop this model year.

There are 753 listings available, which gives you a meaningful amount of inventory to compare.

Is the 2021 GMC Sierra 3500HD a good car?

Yes — the 5/5 user rating points to strong owner satisfaction. The 2021 Sierra 3500HD stands out as a heavy-duty truck that blends serious work capability with a growing list of convenience and towing technology, and it offers a wide range of cab, bed, and rear-axle configurations. That makes it a practical fit if you want a truck that can be configured for demanding jobs while still offering modern convenience features. With 32.9% of listings marked as good or great deals, you also have some room to shop selectively.

Is the 2021 GMC Sierra 3500HD reliable?

Owners rate it 5/5, a strong signal of long-term satisfaction. The 2021 Sierra 3500HD is described as a heavy-duty truck with serious work capability, and it also brings useful standard and available technology that can make day-to-day use easier. For used buyers, the main long-term ownership risk is less about basic usefulness and more about finding a truck that was configured, maintained, and used in a way that matches its heavy-duty purpose.

What should I look for when buying a used 2021 GMC Sierra 3500HD?

Accident-free inventory is solid at 77.6% — always verify the vehicle history report.

You should prioritize a history report first, then focus on a pre-purchase inspection that checks for signs of hard towing or heavy work use. Pay close attention to overall condition, especially on trucks that may have been used for demanding hauling, because the right configuration matters a lot on a heavy-duty pickup like this.

Is now a good time to buy a used 2021 GMC Sierra 3500HD?

This is a moderate market, so you can be selective without expecting every listing to be a bargain.

• Deal availability: 32.9% of listings are priced as good or great deals.
• Inventory: There are 753 listings available.
• Price trend: Prices have softened 7.29% compared with last year.
• Clean inventory: 77.6% of listings are accident-free.

If you find a listing below $51,015, that's toward the low end of the year-round range and worth acting on quickly.

What is the 2021 GMC Sierra 3500HD's resale value?

The current average of $51,015 sits slightly below last year's $55,025.

That price movement suggests the market has cooled a bit, which can help you buy more carefully now but may also mean future resale gains are more limited if prices stay soft. If you plan to sell later, the truck’s value will likely depend heavily on condition, configuration, and how well it has been maintained. Strong demand for capable heavy-duty trucks can help support resale, but the current trend shows you should not expect appreciation in the near term.

Vehicles with strong owner satisfaction ratings, like this model year's 5/5, tend to retain buyer demand, which supports resale value over time.

Should I buy a 2021 GMC Sierra 3500HD or consider a different year?

If you're weighing the 2021 against nearby model years, here's how to think about it:

Choose the 2021 if:

• 32.9% of listings are priced as good or great deals.
• Accident-free inventory is solid at 77.6% — always verify the vehicle history report.
• Price trend: Prices have softened 7.29% compared with last year.
• Owners rate it 5/5 — a strong satisfaction signal.

The bottom line: The 2021 is a strong choice if you want a heavy-duty truck with broad configuration flexibility, solid inventory, and a softer price trend than last year. If you are especially price-sensitive, you may want to compare nearby years and focus on whichever one gives you the best combination of condition, equipment, and asking price.

How does the 2021 GMC Sierra 3500HD compare to the 2021 Ford F-350 Super Duty?

These recommendations are based on CarGurus' proprietary market data from November 10, 2026, CarGurus experts' opinions, and generative AI.