How do I tell what transmission is in my Silverado?

The quickest way to know exactly which transmission your Silverado has is to check the factory build information tied to the vehicle’s VIN, such as the window sticker or build sheet. You can also read the glovebox RPO label or inspect the transmission itself for a model code. If you share your truck’s year and engine, I can give a precise, year-by-year mapping.

Transmissions on Silverado models vary widely by generation and configuration, ranging from older 4-speed automatics to modern 6-, 8-, and even 10-speed units. This article explains reliable methods to identify the exact transmission installed in your truck, using official records first and physical markings second.

VIN and build-sheet methods

These steps rely on factory documentation associated with your specific VIN. They are the most definitive way to determine the exact transmission installed at the factory.

• Locate the Vehicle Identification Number (VIN). It’s on the driver-side dashboard near the windshield, and also on the driver’s door jamb and vehicle’s registration documents.


• Use a GM VIN decoder or pull the build sheet/window sticker for the VIN. The document lists the transmission model that was factory-installed (for example, a 4L60-E, 6L80, 8L90, etc.).


• If you don’t have the sticker handy, ask your Chevrolet dealer to retrieve the build sheet from the VIN or request a copy of the window sticker through GM’s online services or a reputable VIN lookup site.


• Cross-check the engine and drivetrain options on the sheet, since the same engine can be paired with different transmissions in different years or trims.


• Use the documented transmission model as the definitive answer, and note any optional transmissions that might have been available for your exact configuration.

The VIN/build-sheet method is the most reliable way to confirm the transmission that originally came with your Silverado.

On-vehicle labels and physical identification

If factory documents aren’t available, you can often identify the transmission by markings on the transmission itself or by the number of forward gears and the shifter layout.

• Inspect the transmission case for a model code or nameplate. Look on the side of the case near the bellhousing, the pan, or the top. Common GM transmission designations you may see include 4L60-E, 4L65-E, 6L80, 6L90, 8L90, and others depending on year and configuration.


• Check for a metal tag on the transmission with a code and serial number. If present, transcribe the codes and look them up in GM service literature or a reliable parts database to confirm the exact model.


• Observe the gear selector and the number of forward positions. A 4-speed automatic will show fewer forward gear indicators, while 6-, 8-, or 10-speed units will indicate more gears and may have a sport/D/S mode with manual +/- shifts.


• Note the engine type. Some Silverado diesels (Duramax) are paired with an Allison automatic in older/HD configurations; if you have a diesel and see “Allison” on the case or related documentation, that’s a strong clue about the transmission family.

Reading the transmission’s own label or stamping is a solid way to identify the unit when the VIN/build sheet isn’t accessible.

Helpful tips for a precise match

If you want a definitive, year-specific answer, provide your Silverado’s year, engine (gas or diesel), and drivetrain (2WD/4WD). With that information, you can cross-check GM’s official transmission offerings for that configuration and confirm the exact model and gear count.

Summary

To determine which transmission is in your Silverado, start with the VIN to pull the factory build sheet or window sticker, which lists the exact transmission installed. If those documents aren’t available, check the glovebox RPO label for transmission codes, or physically inspect the transmission for a model stamp or nameplate. In many cases, the presence of a Duramax engine points to an Allison transmission, while gasoline Silverado models typically use GM’s 6-, 8-, or 10-speed automatic families. If you share your year and engine, I can give you a precise, model-by-model mapping for your truck.

How do I tell if I have a 4L60 or 6L80?

Control like the other GM automatics the easiest way to identify a 4L80 is to look at the shape of the pan. And you can see compared to this 4L60 pan that the 4L80 pan is just enormous.

How do I find out what transmission I have in my Chevy Silverado?

To find your Silverado's transmission, check the gear selector display to see how many gears shift into, look for the RPO code in the glove box or on the QR code sticker, or use your VIN with a decoder. Common transmissions include the 6-speed 6L80/6L90, 8-speed 8L90, or 10-speed 10L80/10L1000 for different model years and engines. 
This video demonstrates how to check the transmission model by using the gear selector: 49sCodemans autoYouTube · Nov 2, 2023
Method 1: Use the gear selector 

1. Start your truck.
2. Place the gear selector in the Manual (M) or Low (L) position.
3. Press the "+" button on the shifter and count how many gears the display shows before it returns to "D" (Drive). The highest number you reach is the number of speeds in your transmission. 

Method 2: Use the RPO code sticker 

1. Locate the Service Parts Identification (SPID) sticker, which is usually inside the glove box or on the driver's side pillar. 
2. Look for a code that starts with "M," which will indicate the transmission model (e.g., MYC for a 6L80 or 6L90, MYD for a 6L90). 
3. You can also scan the QR code on this sticker with a smartphone app to view all of your vehicle's factory options. 

This video shows how to find and understand the RPO code on the sticker: 1mElectrical Car Repair LIVEYouTube · Jul 23, 2019
Method 3: Use your VIN 

1. Find your Vehicle Identification Number (VIN). It is usually on the driver's side dashboard. 
2. Use an online VIN decoder to find your vehicle's specifications. 
3. Look for the transmission code in the results of the VIN decoder. The fourth through eighth digits of the VIN provide information on the model, body type, and transmission. 

You can watch this video to learn about different types of transmissions: 20sSpeedway MotorsYouTube · May 15, 2025

Will my VIN number tell me what transmission I have?

Yes, you can often tell your transmission type by checking the VIN, but it's not guaranteed because transmission data isn't always encoded in the VIN according to a single standard. To find out for sure, you can use the VIN with an online decoder like the NHTSA VIN decoder, check with a dealership's parts department, or look for physical identifiers on the vehicle itself. 
How to find your transmission using the VIN

• Use an online VIN decoder: Input your 17-character VIN into a decoder, such as the one provided by the National Highway Traffic Safety Administration (NHTSA). Look for a "Transmission" or "Engine" category in the results. This is the most direct way, but it may only provide basic information like "manual" or "automatic". 
• Contact a dealership: Provide the VIN to the parts department of your vehicle's dealership. They can look up your specific vehicle's original factory options and tell you the exact transmission it was built with. 
• Check the vehicle's build sheet or window sticker: If you have them, these documents will list the original factory options for your vehicle, including the transmission type. 
• Use a specialized decoder (if available): For certain vehicle brands, like BMW, there are specialized online resources (e.g., RealOEM) that can provide detailed information by inputting the last seven digits of the VIN. 

If the VIN doesn't provide the answer

• Inspect the physical transmission: Crawl under the vehicle and look for a tag on the transmission itself, which will have a specific model number. You can also get a general idea of the type by looking at the shape of the oil pan or checking online for images of your vehicle's transmission.
• Provide other vehicle information: If the VIN decoder doesn't work, provide your vehicle's make, model, year, and engine size to a knowledgeable person or online forum, and they may be able to determine the correct transmission based on that information. 

How do I know if I have a 6L80 or 6L90?

The main ways to identify a 6L80 from a 6L90 are by the RPO code (6L80=MYC, 6L90=MYD), the length, and the pan shape. The 6L90 is a heavier-duty version that is approximately 1-3/8 inches longer and has a pan with a flatter corner, while the 6L80 is shorter and has a more rounded pan corner. You can also check the part numbers or look at specific internal components if you have the transmission disassembled.
 
This video explains the difference between 6L80 and 6L90 valve bodies: 57sBrad's TransmissionYouTube · Apr 24, 2024
Key identification methods 
This video shows how to identify a transmission by using the gear selector on the dashboard: 52sCodemans autoYouTube · Nov 2, 2023

• RPO Code: Look for the RPO (Regular Production Option) code on the glovebox or vehicle service tag. 
  • MYC: indicates a 6L80. 
  • MYD: indicates a 6L90. 
• Transmission Length: The 6L90 is longer than the 6L80. 
  • 6L80: Case with bell housing length is approximately 23.5 inches. 
  • 6L90: Case with bell housing length is approximately 25 inches (1-3/8 inches longer). 
• Transmission Pan: The shape of the transmission pan is a reliable indicator when the unit is out of the vehicle. 
  • 6L80: The pan has a rounded corner on the back. 
  • 6L90: The pan has a flatter corner on the back. 
• Part Numbers: GM part numbers for transmission parts often begin with 242. The specific part number on the TEHCM sticker (under the transmission pan) can help identify the exact model and year. 

This video discusses the size differences between 6L80 and 8L90 transmissions: 1mSwap TimeYouTube · Feb 19, 2020