Used 2021 GMC Sierra 3500HD for Sale near Ontario

How much does the 2021 GMC Sierra 3500HD cost?

Prices have softened 9.88% compared to this time last year, making it a favourable time to shop this model year.

There are 98 listings available, which gives you a modest amount of inventory to compare before you buy.

Is the 2021 GMC Sierra 3500HD a good car?

Yes — the 5/5 user rating points to strong owner satisfaction, and the overview shows why: you get serious heavy-duty capability, a broad range of cab, bed, axle, and trim combinations, and a more polished feel than many buyers expect from a truck this capable. It also suits both work-focused buyers and shoppers who want a more refined, feature-rich setup.

The market currently shows 23.5% of listings 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 overview suggests a truck built around substantial capability and a broad configuration range, which can be a plus if you need something tailored to your use case. For used buyers, the main long-term ownership risk is making sure the truck’s heavy-duty hardware and towing-focused equipment have been maintained properly.

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

This is a moderate market for selective buyers, so you can shop with some patience and still find worthwhile listings.

• Deal availability: 23.5% of listings are priced as good or great deals.
• Inventory: There are 98 listings available.
• Price trend: Prices have softened 9.88% compared with last year.

If you find a listing below $62,087 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 $63,775 CAD sits slightly below last year's $70,767 CAD.

That kind of price movement suggests the market has become more favourable for buyers, but it also means a future seller may need to price competitively to stand out. If you buy well now, you may have a better chance of limiting depreciation pressure later. The truck’s broad appeal and heavy-duty capability should help keep interest steady among shoppers who need real towing and hauling strength.

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:

• 23.5% of listings are priced as good or great deals.
• Price trend: Prices have softened 9.88% compared with last year.
• Owners rate it 5/5 — a strong satisfaction signal.

The bottom line: The 2021 is the right pick if you want a heavy-duty truck with strong capability, a polished feel, and a market that currently gives you some negotiating room. If you’re especially price-sensitive, a nearby year may be worth comparing, but the 2021 stands out as a balanced choice when you want capability and value to line up.

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 October 27, 2026, CarGurus experts' opinions, and generative AI.