2021 Used GMC Engines For Sale

13
verified 2021 GMC engines
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Up to 3 yrs
extended warranty available
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shipment

2021 Used GMC Engines For Sale

13 verified used 2021 GMC engines in stock, every one matched by RPO option code and the 8th VIN digit before it ships — the 3.6L LGX in the Acadia against the 3.6L LGZ in the Canyon, the 4.3L LV1 in the Savana against the 4.3L LV3 in the Sierra 1500, and the 6.6L L8T gasoline big block. Free freight, photos before we ship, 30 days to return.

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Warranty On Every Unit
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Photos Before Shipment
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ASE-Tested & Verified
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Free Nationwide Shipping
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30-Day Money-Back
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2021 GMC Engines In Stock by Model

Live inventory for model year 2021 — every model we hold, with the number of listed units for each. Tap one to jump to the listings.

Acadia4 units2.0L LSY · 2.5L LCV · 3.6L LGXSierra 15002 units2.7L L3B · 4.3L LV3Savana 2500 / 35002 units4.3L LV1 van V6Terrain2 units1.5L LYX turbo, FWD and AWDCanyon2 units2.5L LCV 4x2 · 3.6L LGZSierra 2500 HD1 unit6.6L L8T gasoline V8

2021 GMC Engine Families

Which engine sits under which 2021 GMC, and how many of each we hold today.

Engine family Fits (2021) In stock
3.6L LGX V6 Acadia AT4 and Denali — with and without Opt V08 heavy-duty cooling 2
2.5L LCV Four Acadia FWD, Canyon 4x2 — the only RPO shared across a car and a truck this year 2
4.3L LV1 V6 Savana 2500, Savana 3500 — van-specific 4.3L, not the Sierra's LV3 2
1.5L LYX Turbo Four Terrain FWD and AWD 2
6.6L L8T Gas V8 Sierra 2500 HD — gasoline big block, not the L5P Duramax 1
3.6L LGZ V6 Canyon — same 3.6L displacement as the Acadia's LGX, different engine 1
4.3L LV3 EcoTec3 V6 Sierra 1500 base — shares displacement with the Savana's LV1 only 1
2.7L L3B TurboMax Four Sierra 1500 1
2.0L LSY Turbo Four Acadia 1
Total 13

Other GMC Model Years

Every model year we hold GMC engines for. Years without a link are in stock but have no year page yet — text us your VIN.

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Why Buy a 2021 GMC Engine from Auto Power Source

2021 is the model year where GMC's displacement badges stop telling you anything useful. Two separate 3.6L V6s were sold that year — the LGX in the Acadia and the LGZ in the Canyon — and two separate 4.3L V6s, the LV1 in the Savana vans and the LV3 EcoTec3 in the base Sierra 1500. Each pair reads identically on paper and shares neither part numbers nor accessory mounting. The RPO option code on the service parts identification label, and the 8th digit of the VIN, are what separate them.

The 2.5L LCV is the one RPO that genuinely crosses the lineup in 2021: the same four-cylinder appears in the front-wheel-drive Acadia and in the Canyon 4x2. The Acadia also carried the 2.0L LSY turbo four, and the Terrain ran the 1.5L LYX turbo in both FWD and AWD. On the truck side the Sierra 1500 split between the 2.7L L3B TurboMax four and the 4.3L LV3, while the Sierra 2500 HD unit we hold is the 6.6L L8T — the gasoline big block, not the L5P Duramax that shares its displacement.

The Acadia's 3.6L LGX is listed two ways because GMC built it two ways: with Opt V08 heavy-duty cooling and without. That is a cooling-package split inside one engine family, and we list it explicitly rather than hiding it behind one line. Every unit here is used OEM pulled from a low-mileage donor vehicle, cataloged against its VIN, compression-tested and leak-down evaluated by ASE-certified technicians, photographed for your approval, and shipped free on a pallet with 30 days to return it.

📱 Fastest way to match: text us your VIN, get options in minutes.Text Your VIN →

Your 2021 GMC Engine Options: Compared

Most 2021 GMC owners face four real choices when the engine fails:

← Swipe sideways to see all columns →
Option Cost Reliability Warranty Fitment Match
Used OEM (this collection) $$$ Best Value High — tested Included VIN-matched
New OEM (dealer) $$$$$ 2-4× more High Manufacturer Exact
Aftermarket / Reman $$$$ Varies 6-12 mo May adapt
Junkyard $ Cheapest Unknown None DIY

Tested used OEM hits the sweet spot — same engineering as new, fraction of the cost.

2021 GMC Engine Buying Guide

5 things to verify before buying a used 2021 GMC engine:

  1. Decide which 3.6L V6 you need before anything else. The LGX is the Acadia unit (VIN S); the LGZ is the Canyon unit (VIN N). Both are listed as 3.6L on a 2021 GMC. They are different engines with different part numbers and will not swap.
  2. The two 4.3L V6s are not the same engine either. LV1 (VIN P) is the Savana 2500 and 3500 van V6; LV3 (VIN H) is the EcoTec3 in the base Sierra 1500. Same displacement, separate families, no interchange.
  3. Read the RPO code, not just the displacement. GMC identifies 2021 hardware by option code — LGX, LGZ, LCV, LV1, LV3, LYX, L3B, LSY, L8T. The code appears on the service parts identification label and is the fastest way to confirm what came out of your vehicle.
  4. Check the cooling package on an Acadia 3.6L. The LGX was built with and without Opt V08 heavy-duty cooling. Both are in stock here and listed separately, because the radiator, fan and plumbing differ even though the engine family does not.
  5. Confirm the match with your own VIN before you order. Your VIN settles the engine code, drivetrain and build split in one step. Text it to +1-307-441-5554 and we will confirm in writing exactly which unit fits your vehicle before you pay.

Our ASE-certified technicians verify every one of these points against your VIN before any unit ships.

📞 Need help choosing the right 2021 GMC engine? Talk to our team live.Call 1-877-313-8995

Frequently Asked Questions

What is the warranty on a used 2021 GMC engine?
Every 2021 GMC engine ships with a warranty included, printed on each product page. Extended coverage of up to 3 years is available at checkout.
What does ASE-tested mean?
ASE-certified technicians compression-test every cylinder and run a leak-down evaluation, then noise and smoke verification, a full visual inspection, and multi-angle photography before shipment.
How long until delivery?
Prep and ship is 3-5 business days, transit 2-3 business days after dispatch by freight carrier.
Can I see photos before I buy?
Yes. Multi-angle photos of the actual unit are sent before payment. If you do not approve them, you get every dollar back.
Do I need my VIN?
Yes. On a 2021 GMC the 8th digit separates the 3.6L LGX from the 3.6L LGZ and the 4.3L LV1 from the 4.3L LV3. Text your VIN to +1-307-441-5554.
Which 2021 GMC models do you stock?
Acadia, Sierra 1500, Sierra 2500 HD, Savana 2500 and 3500, Terrain and Canyon.
Why cheaper than dealer new?
Used OEM from low-mileage donor vehicles — the same GM engineering and the same RPO-coded hardware, at a fraction of a new crate price.
When can I reach customer service?
Call 1-877-313-8995 or text +1-307-441-5554 during the hours in the site footer, or email info@autopowersource.com.
🏆 Earn $500 with Our Rewards Program
Every GMC engine you buy earns rewards. 10 orders (yours or referred) = $500 cash credit. Silver, Gold, and Platinum tiers with discounts, priority support, and private inventory access.
See How Rewards Work →
100K+
Engines+Transmissions In Stock
0%
fitment-related returns
All 50
states covered, free freight
36
brands covered

Our 6-Step Inspection & Shipping Process

Every 2021 GMC engine we ship has been through these six steps:

1. VIN-Matching
We match the donor VIN to your VIN to confirm engine code, generation, emissions calibration, and drivetrain fit.
2. Tested & Verified
ASE-certified technicians compression-test every cylinder and run leak-down evaluation on engines. Transmissions are Shift-Tested through all gears.
3. Noise & Smoke Verification
Units are run to verify normal mechanical sound and clean operation — catches internal wear static tests miss.
4. Visual Inspection
Every accessible component is inspected: turbos, manifolds, valve covers, AFM/DFM lifters, accessories, sensor harnesses.
5. Photograph & Catalog
Multi-angle photos sent to you BEFORE we ship for your approval.
6. Palletize & Ship
Strapped on a heavy-duty wooden pallet, shipped via freight at no charge.

Our Photos-Before-Shipment Guarantee

Before any engine leaves our warehouse, we send you multi-angle photographs. You approve. If you do not approve, you get every dollar back — no questions, no restocking fees, no return freight charges. On top of 30-day money-back and the warranty included with every unit. Browse all 13 2021 GMC engines below.

✉ Email Us at info@autopowersource.com
No match? Text VIN →