How do I know what rear axle ratio my Silverado has?
The rear axle ratio is the gear ratio of the truck’s rear differential. You can confirm it by reading the factory axle code on the door sticker or differential tag, or by decoding the VIN/build sheet through GM’s resources. This number matters for towing, maintenance, and parts compatibility.
Reliable identification involves checking common data sources like the door jamb label, the differential area, or the vehicle’s VIN/build sheet. Below are the main methods used by owners and technicians to pin down the exact ratio for most Silverado models built in the last decade.
Where to look on the vehicle
Use these checks to locate the axle ratio directly on the truck.
- Door jamb sticker: The driver's door jamb sticker typically lists configuration data including the axle ratio as "AXLE" followed by a number such as 3.23, 3.42, 3.73, or 4.10. If your sticker uses codes, refer to GM’s code charts for mapping.
- Differential tag or stamping: Lift the vehicle safely and inspect the differential cover or the back of the differential housing for a stamped number that corresponds to the axle ratio. Some models place the ratio directly on the ring-gear housing.
- Differential cover label: A small tag on the differential cover may display the axle ratio along with other manufacturing data.
Because GM uses both direct numeric displays and codes, cross-check with the VIN or build information if a sticker is missing or faded.
How to decode the VIN/build sheet to find the axle ratio
If labeling is unclear or absent, decoding the VIN or production build sheet provides a definitive answer.
- Locate the 17-character VIN on the dash, the driver’s door jamb, or the vehicle registration.
- Access GM’s official VIN decoder (or your dealership’s service portal) to pull the axle-related RPO codes associated with your vehicle.
- Cross-check the axle-related RPO code with GM’s published codes to determine the exact ratio (some years show the numeric ratio directly, others require a code lookup).
- If you can’t access online resources, contact a GM dealer with the VIN and request the exact axle ratio for your build.
VIN-based decoding is the most reliable way to confirm the axle ratio, especially for used trucks where stickers may be missing or altered.
Practical notes for Silverado configurations
Axle choices vary by year, engine, drivetrain, and tow/HD packages. Here are general patterns you might see, but always verify with the methods above.
- Common 1500 configurations include 3.23, 3.42, 3.73, and 4.10 gears, with the latter two more common on tow/HD or higher-trim packages.
- 4x4 models frequently use 3.42 or 3.73, though some packages may employ other ratios for specific towing or off-road goals.
- Diesel and heavy-duty variants have their own axle options as part of specific option codes, so VIN decode or dealer data is especially helpful for these trucks.
Knowing the exact ratio helps with towing calculations, maintenance intervals, and selecting compatible parts such as transmission governors or differential fluids.
What to do if you can’t find any label
Faded stickers or missing data can happen. Try these options to recover the information.
- Original documents: If you have the window sticker, build sheet, or sales invoice, the axle ratio is listed there as part of the build options.
- Dealership assistance: A GM technician can pull the precise axle ratio from the VIN using OEM tools; they can confirm the exact gear count for your truck.
In most cases, a dealer or VIN-based lookup will reveal the correct axle ratio. This ensures accuracy for maintenance and parts compatibility.
Summary
The rear axle ratio in a Silverado is the gear ratio of the rear differential. It can be found on the door jamb label, on the differential tag or stamp, or by decoding the VIN/build sheet via GM’s official resources. If any label is illegible, VIN-based lookups through a dealer or GM’s owner portal provide a reliable path to the exact figure. With the right data, you can plan maintenance, towing, and modifications with confidence.
