How do I know what transmission I have in my Chevy 1500?
You can identify the transmission by inspecting the physical unit for a model stamp, checking the RPO (Regular Production Option) codes on the glovebox or door stickers, reviewing the vehicle’s build sheet or window sticker, or confirming the original and current setup with the VIN through a dealer or GM’s decoder.
Start with the transmission itself
Many GM transmissions carry a metal tag or a stamped/model code on the side of the case. Look for markings such as the transmission model (for example, 4L60-E, 6L80, 8L90) on the housing or near the bellhousing. In some cases the code is stamped on the pan or on a boss on the side of the casing. Clean the area carefully and photograph any numbers you find to share with a technician or dealer.
Where to look on the transmission
The model name or code is typically found on the side of the case or on a small ID tag attached to the housing. If you’re unsure what you’re seeing, take a clear photo and compare it to a transmission guide or show it to a shop for verification.
Knowing the exact transmission model helps you source the correct fluid, filter, and maintenance schedule, and it clarifies which service bulletins could apply to your truck.
Check the glovebox or driver's door sticker for RPO codes
The GM glovebox or driver’s door jamb often carries an RPO sticker listing factory-installed options, sometimes including a Transmission code or label. This code indicates the transmission family that originally came with the truck. Compare the code to GM’s official RPO lists or ask a dealer to translate it into a specific transmission model.
What the sticker can tell you
Look for a line that references the transmission or a code that corresponds to the transmission option. Codes vary by year and trim, so a dealer or GM’s decoder is the best way to confirm the exact model from the sticker alone.
If the sticker is missing or damaged, this method may be less reliable, but it remains a good starting point when combined with other checks.
Review the build sheet or window sticker
The vehicle’s official build sheet (sometimes called the build manifest) or window sticker (Monroney label) lists the original drivetrain configuration, including the transmission. If you can access the window sticker from the vehicle’s dealer records or via online VIN lookups, you’ll often see the exact transmission designation alongside the engine and axle details.
Why this matters
The build sheet reflects what the factory installed at the time of manufacture. If the truck has had a transmission swap since leaving the factory, this method will still help you distinguish the original equipment from the current installation.
Cross-checking with the physical transmission and the VIN-backed sources helps you confirm both originality and current configuration.
Use the VIN to verify with a dealer or GM decoder
Your 17-digit VIN can be used to pull drivetrain specifications from GM’s official VIN decoder or your local dealer’s system. Some reputable third-party decoders can also provide transmission details, but accuracy varies. If you suspect a swap, verify the installed unit against the VIN’s original spec and service history.
What you’ll typically do
Provide the VIN to a GM dealer or use an official online VIN tool. If the truck has undergone a transmission replacement, the VIN lookup may reflect the original equipment rather than the current unit, so verify with service records or the installed tag on the transmission itself.
What to consider if the truck has been modified or swapped
If a previous owner replaced the transmission or modified the drivetrain, the current transmission may differ from the factory option listed by the VIN. In such cases, rely on the current transmission tag and the service history to identify the installed unit, and have a trained technician confirm compatibility for maintenance and parts.
Practical steps
Inspect the current transmission directly, compare the model stamp to known options, and request a written service history from the seller or shop. When in doubt, a dealer’s service department can confirm both the original and current configuration using the VIN and the transmission’s identification tag.
Putting it all together
By combining a direct read on the transmission, the RPO codes on interior stickers, the build sheet/window sticker, and a VIN-based check with a dealer, you’ll have a clear picture of which transmission your Chevy 1500 uses. This knowledge supports proper maintenance, fluid specification, parts compatibility, and potential software updates.
Summary
To determine the transmission in your Chevy 1500, identify the model stamped on the transmission housing, read any RPO or Transmission codes on interior stickers, consult the build sheet or window sticker, and verify via the VIN with a dealer or GM’s official decoder. If the vehicle might have been modified, prioritize the actual installed unit’s identification tag and service history for the most accurate answer.
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
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.
Can a VIN number tell me what transmission I have on my Chevy?
Digits in position 4 through 9 make up the Vehicle Description Section (VDS). The fourth through eighth digits describe your vehicle's model, body type, restraint system, transmission type, and engine code.
How do I tell what transmission I have on my Chevy Silverado 1500?
One you will come right over here on the shifter. And you see See the plus. You're just going to push that. Up.
