Prices starting at: $47,900

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Learn More About Buying a 2026 GMC Sierra 3500 HD in O'Fallon

Visit O'Fallon Buick GMC for a great deal on a new 2026 GMC Sierra 3500 HD. Our sales team is ready to show you all of the features that you will find in the GMC Sierra 3500 HD and take you for a test drive in the O'Fallon Area. At our GMC dealership you will find competitive prices, a stocked inventory of 2026 GMC Sierra 3500 HD cars and a helpful sales team. Stop by our car dealership today and take a 2026 GMC for a spin.

2026 GMC Sierra 3500 HD Truck

2026 GMC Sierra 3500 HD Pro

  • MSRP$70,715
  • Discount$2,121
  • Price$68,594
  • Offers$500
  • Final Price$68,094
  • Conditional Offers$1,000
Engine: 6.6L Duramax Turbo-Diesel V8 engine, Transmission: Automatic, Exterior Color: Onyx Black, Interior Color: Jet Black, Cloth seat trim
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View All New GMC Sierra 3500 HD

Sorry, no GMC Sierra 3500 HDs are currently in stock.

We may have vehicles that have not yet posted to the website, so we request you call us at (636) 200-3388 for further assistance!

GMC (1)

Sierra 3500 HD Truck (4)

2026

Manufacturer Offer

For Well-Qualified Buyers When Financed w/ GM Financial

  1. 4.9% APR for 36 months
  2. 4.9% APR for 48 months
  3. 5.9% APR for 60 months
  4. 6.9% APR for 72 months
  • Applies to this new 2026 GMC Sierra 3500 HD

For Well-Qualified Buyers When Financed w/ GM Financial

Disclaimer(s)
  • 4.9% APR for 48 months for well-qualified buyers when financed w/GM Financial. Monthly payment is $22.98 for every $1000 you finance. Average example down payment is 10.0%. Not available with leases and some other offers. Must take new retail delivery by 01/02/2026. Truth in Lending Act Disclosure: Down payment will vary with APR and credit. For example, 4.9% APR with $2,500 down payment provides for 48 monthly payments of $22.98 per $1000 financed for qualified buyers. 4.9% APR for a term of 36 months corresponds to a monthly cost of $29.93 per $1000 financed. 6.9% APR for a term of 84 months corresponds to a monthly cost of $15.04 per $1000 financed. 6.9% APR for a term of 72 months corresponds to a monthly cost of $17 per $1000 financed. 5.9% APR for a term of 60 months corresponds to a monthly cost of $19.29 per $1000 financed. The rates described are for estimation purposes only; you may not be able to finance at this rate. (See Trims)
  • See State Disclaimer *
Manufacturer Offer

Purchase Allowance

  1. $500 Cash
  • Applies to this new 2026 GMC Sierra 3500 HD

Disclaimer(s)
  • Not available with special financing, lease and some other offers. Must take new retail delivery by 01/02/2026. (See Trims)
  • See State Disclaimer *
Manufacturer Offer

GM Military Offer

  1. $500 Offer
  • Applies to this new 2026 GMC Sierra 3500 HD

Disclaimer(s)
  • Eligible military personnel includes Active Duty members, Reservists, National Guard members, Veterans and Retirees of the U.S. Army, Navy, Air Force, Marine Corps and Coast Guard. Eligible participants are able to sponsor their spouse. At participating dealers only. Visit gmmilitaryappreciation.com for program eligibility details and for a list of eligible vehicles. Not available with some other offers. Must provide authorization number to participating dealer prior to or at time of vehicle delivery to receive offer. Must take new retail delivery by 01/02/2026. (See Trims)
  • See State Disclaimer *
Manufacturer Offer

GM First Responder Offer

  1. $500 Offer
  • Applies to this new 2026 GMC Sierra 3500 HD

Disclaimer(s)
  • Must be a current Firefighter, Police, EMT/Paramedic, or 911 Dispatcher. First Responders employed by federal, state or municipal governments may be subject to restrictions that limit their ability to accept this offer. Accordingly, this offer is void unless permitted by applicable federal, state and municipal laws, regulations, rules, ordinances, policies, codes of conduct, and other directives or standards regarding ethics and gift acceptance by the applicable federal, state or municipal employees. By accepting this offer, you verify that doing so complies with all laws, regulations, policies or other restrictions regarding ethics or gift acceptance that apply to you. Eligible participants are able to sponsor their spouse. At participating dealers only. Visit gmfirstresponderappreciation.com for program eligibility details and for a list of eligible vehicles. Not available with some other offers. Must provide authorization number to participating dealer prior to or at time of vehicle delivery to receive offer. Must take new retail delivery by 01/02/2026. (See Trims)
  • See State Disclaimer *

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Disclaimer: The Manufacturer’s Suggested Retail Price excludes tax, title, license, dealer fees and optional equipment. Dealer sets final price.

1Dealer Discount applied to everyone