Used 2021 GMC Sierra 3500HD for Sale near Ontario

How much does the 2021 GMC Sierra 3500HD cost?

Prices have softened 13.15% compared to this time last year, making it a favourable time to shop this model year.

There are 68 listings available, which suggests you have a reasonable amount of inventory to compare.

Is the 2021 GMC Sierra 3500HD a good car?

Yes — 5/5 is a strong user rating for this heavy-duty truck. The 2021 GMC Sierra 3500HD stands out as a heavy-duty pickup that blends serious work capability with a more polished feel than many trucks in its class. It was part of the fifth generation, which brought a larger footprint, revised styling, and meaningful gains in maximum towing capacity. You also get a wide range of cab, bed, and rear-axle configurations, so you can tailor it closely to work needs.

For buyers who want maximum capability with a refined cabin and useful towing technology, it is a compelling choice. 25.0% of listings are priced as good or great deals, which gives you 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 GMC Sierra 3500HD was built as a serious work truck with a polished feel, and its equipment list reflects that balance. Even the base model included a seven-inch infotainment touchscreen, Apple CarPlay and Android Auto, keyless entry, cruise control, and a trailer hitch receiver with hitch guidance, while higher trims added features such as leather upholstery, dual-zone climate control, a Bose premium audio system, and a head-up display.

For used buyers, the main long-term ownership risk is less about basic capability and more about the realities of living with a very large, heavy-duty truck, especially if you plan to use it in tight spaces or keep it in higher-spec form.

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

This is a moderate market, so you can shop carefully without feeling rushed, but the best listings may still move quickly.

• Deal availability: 25.0% of listings are priced as good or great deals.
• Inventory: There are 68 listings available.
• Price trend: Prices have softened 13.15% compared with last year.

If you find a listing below $62,371 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 $62,445 CAD sits slightly below last year's $71,904 CAD.

That price movement suggests the market has already adjusted downward, which can help you as a buyer today but may limit upside if you plan to resell soon. For a future seller, the softer pricing means you may need to be more competitive on asking price to stand out. The truck’s strong capability and broad configuration range should still support demand among shoppers who need a one-ton pickup.

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:

• 25.0% of listings are priced as good or great deals.
• Price trend: Prices have softened 13.15% 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 refined cabin, and a market that has become more favourable on price, the 2021 is the better all-around pick. If you are especially price-sensitive, you can also compare nearby years to see whether a similar truck offers a lower entry point, but the 2021 remains the most balanced choice for shoppers who value capability and equipment.

These recommendations are based on CarGurus' proprietary market data from September 11, 2026, CarGurus experts' opinions, and generative AI.