Used 2021 GMC Sierra 3500HD for SaleNationwide

How much does the 2021 GMC Sierra 3500HD cost?

Prices have softened 11.67% compared to this time last year, making it a favourable time to shop this model year.

There are 88 listings available, which gives you a modest amount of inventory to compare before you decide.

Is the 2021 GMC Sierra 3500HD a good car?

Yes — the 5/5 user rating suggests you may be looking at a truck that satisfies owners very well. The 2021 GMC Sierra 3500HD stands out as a heavy-duty truck that blends serious work capability with a more polished feel than many buyers might expect, and its broad range of cab, bed, axle, and trim combinations makes it flexible for both basic work use and more upscale setups. For you, that means it can fit a wide range of heavy-duty needs without forcing you into a single configuration. With 22.7% of listings marked as good or great deals, there is still some room to shop carefully.

Is the 2021 GMC Sierra 3500HD reliable?

Owners rate it 5/5, a strong signal of long-term satisfaction.

The 2021 GMC Sierra 3500HD is described as a heavy-duty truck that combines strong hauling and towing ability with smart towing technology and a broad configuration range, which are all traits that can support confidence in day-to-day use. It also gained a new jack-knife alert system and the MultiPro tailgate for 2021, adding useful equipment to its work-focused mission. For used buyers, the main long-term ownership risk is that a truck built for serious towing and hauling may have seen demanding use, so condition and maintenance history matter.

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

This looks like a moderate, selective buyer’s market, so you can afford to be patient and compare listings carefully.

• Deal availability: 22.7% of listings are priced as good or great deals.
• Inventory: There are 88 listings available.
• Price trend: Prices have softened 11.67% compared with last year.

If you find a listing below $62,089 CAD, 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 $63,832 CAD sits slightly below last year's $72,262 CAD.

That drop suggests the market has become more favourable for buyers, but it also means a future seller may need to price more competitively than owners did a year ago. The current range still leaves room for stronger examples to hold value better than average, especially if they are well equipped and in good condition. Because the truck has broad appeal across work and higher-end use cases, demand should remain reasonably steady for the right configuration.

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:

• 22.7% of listings are priced as good or great deals.
• Price trend: Prices have softened 11.67% compared with last year.
• Owners rate it 5/5 — a strong satisfaction signal.

The bottom line: If you want a heavy-duty truck with strong capability, a more polished feel, and a broad range of configurations, the 2021 is the primary year to target. If you are more price-sensitive, you may also want to compare nearby years and focus on whichever one gives you the best condition and equipment for the money.

These recommendations are based on CarGurus' proprietary market data from October 13, 2026, CarGurus experts' opinions, and generative AI.