Coverage: Varies by model year and VIN; the free check tells you before you pay
Why check the sticker on a used Sierra?
The window sticker, or Monroney label, is the federally required price label that was on the glass when the truck or SUV was new. On a GMC it lists the model and trim, the standard equipment, every factory option and package with its price, the destination charge, the total MSRP, the EPA fuel economy figures and the assembly plant.
That matters with GMC because two trucks with the same badge can be very different. A Sierra 1500 SLT with a few add-ons and a fully loaded one can be far apart on the original sticker, even though they look alike on the lot. The sticker is the quickest way to see which one you are looking at.
Where is the RPO label on a GMC truck?
- VIN plate: on the driver’s side of the dashboard, readable through the windshield. It is also printed on the certification label in the driver’s door opening.
- Certification label: on most GM vehicles it sits on the driver’s side B-pillar. From the 2018 model year, GM added a QR code to this label on GMC, Chevrolet, Buick and Cadillac models. Scanning it with a phone shows the VIN, model year, build date, the three-character RPO codes and the paint code.
- Service Parts Identification (SPID) label: older GMCs carry their RPO list on a printed sticker, most often in the glove box. GMC moved it around from year to year, so check the glove box first, then the door and console.
What do GMC codes like L5P and LM2 mean?
GM identifies every factory option with a three-character Regular Production Option (RPO) code. Engines have them (L5P is the 6.6L Duramax diesel in the Sierra HD, and LM2 is the 3.0L Duramax in the Sierra 1500 and Yukon), and so do paint, axles, seats and packages.
GM paint codes come in two forms. The label shows a short three-character color RPO, such as GAZ, and paint suppliers often use a longer “WA” number for the same color. Neither appears in the VIN itself; our paint code guide explains why, and the GM paint code guide covers GM’s color codes.
On the window sticker, the options are written out in plain English with prices. The RPO codes are on the label and in the build data, which is why the GM build sheet and the sticker work well together.
What’s the difference between AT4, Denali and other GMC trims?
GMC sells trucks, SUVs and vans, and its trim names repeat across the lineup:
| Model | Type |
|---|---|
| Sierra 1500, Sierra 2500HD, Sierra 3500HD | Pickups |
| Sierra EV, Hummer EV Pickup, Hummer EV SUV | Electric |
| Canyon | Mid-size pickup |
| Terrain, Acadia | Crossovers |
| Yukon, Yukon XL | Full-size SUVs |
| Savana | Vans |
For the 2025 Sierra 1500, GMC offered eight trims: Pro, SLE, Elevation, SLT, AT4, AT4X, Denali and Denali Ultimate. AT4 and AT4X are the off-road trims with extra lift and underbody protection. Denali and Denali Ultimate are the luxury trims. The same naming shows up on the Yukon, Canyon and Acadia, so the sticker is where you confirm which trim and which packages were actually ordered.
How do I get a Sierra or Yukon window sticker by VIN?
Enter the 17-character VIN from the Sierra, Yukon or other GMC. Our licensed window-sticker data partner checks whether the original sticker is on file, and the result appears before checkout. You get the NHTSA decode, trim and recall count free, and can look up open recalls on that VIN at nhtsa.gov/recalls. If the sticker is there, the $9.99 Full Report adds the original PDF, each option and package with its price, the paint code where we can match it, and full recall details. On-file coverage changes with the model year. If we say a sticker is available and fail to deliver it, we refund you automatically.
If none is on file: you still have good options. Scan the QR code on the B-pillar certification label (2018 and later) or read the glove box SPID label for the full RPO list. A GMC dealer’s service department can look up the original build from the VIN, and GMC Customer Assistance is at 1-800-462-8782, and owner support is on gmc.com. The original purchase paperwork, if the seller has it, usually lists the same options as the sticker.
If you’re comparing a GMC with its Chevrolet twin, the Chevy window sticker page covers the Silverado and Tahoe side.
Last updated November 5, 2026.
