How do I know what rear differential is in my Silverado?
To determine your Silverado’s rear differential quickly, check the axle code on the SPID label in the driver’s door jamb (and/or the glove box build sheet), then verify with the VIN via a GM VIN decoder or dealer tool, and look for a G80 tag on the axle housing to confirm if a locking differential is equipped.
Where to find the axle information
Start with the most accessible sources first. The following identifiers are the most reliable for identifying gear ratio and differential type across model years and trims.
- Door jamb SPID label: Look for the line labeled AXLE. It usually lists the gear ratio (for example, AXLE 3.42) and may also indicate a locking differential (G80) if equipped.
- Vehicle build sheet or window sticker: The SPID data printed on these documents lists the axle ratio and differential option; a dealer can pull this data from the VIN if the sticker isn’t present.
- VIN-based decoding: Use a GM VIN decoder or dealer service tool to retrieve the axle ratio and whether a locking differential is included. This is often the quickest way to confirm the exact configuration.
- Axle housing tags or stamping: Some rear axles carry a metal tag or stamping on the differential housing that identifies the ratio or the locker option (such as G80).
- Model-year and trim context: Knowing your truck’s year, model (1500/2500/3500), and drive (2WD/4WD) helps narrow possibilities and guides you to the most likely configurations before you confirm with sources above.
Using these sources in combination will give you a reliable answer about your Silverado’s rear differential.
Interpreting the codes and what they mean
Understanding the axle code helps with towing performance, fuel economy, and parts compatibility. The most common items you’ll encounter are the gear ratio (for example 3.23, 3.42, 3.73) and whether the axle is equipped with a locking differential (G80) or an open/LSD configuration depending on the option package.
Axle ratio numbers
The gear ratio indicates how many turns the driveshaft makes for one revolution of the wheel. A lower ratio (e.g., around 3.23) favors highway efficiency, while a higher ratio (e.g., 3.73 or higher) improves towing and launch performance. The exact ratio on your vehicle is listed on the SPID label or VIN decoder results.
Locking vs open differentials
A G80 code on the SPID label or a tag on the rear axle indicates a locking differential, which can actively bias power to one wheel when needed. If no G80 tag/code appears, your Silverado likely uses an open differential or a different limited-slip setup depending on the build package.
Practical steps to confirm your exact spec
If you’re about to order parts, plan towing, or want precise maintenance guidance, confirm the exact rear differential using these methods.
- Check the driver’s door jamb SPID label for AXLE and the ratio; note any G80 indication.
- Review the glove box build sheet or window sticker for the axle data.
- Use the VIN to pull the build data from a GM VIN decoder or have a dealer run the VIN for the exact axle specification.
- Inspect the axle housing for a metal tag or stamped code indicating the ratio or the G80 locker option.
Cross-checking these sources will give you a precise picture of your Silverado’s rear differential.
When you should verify with a dealer or service professional
If you’re unsure or the data seems inconsistent across sources, contact a Chevrolet dealer with your VIN. They can pull the official RPO codes and build sheet data to confirm the exact axle ratio and whether a locking differential is installed.
Summary
The easiest way to determine your Silverado’s rear differential is to locate the AXLE entry on the SPID label in the driver’s door jamb, then cross-check with the vehicle’s VIN using a GM VIN decoder or dealer tools. Look for a G80 tag or mention of a locker to confirm if you have a locking differential. By checking multiple sources—SPID label, build sheet/sticker, VIN decoder, and any axle tags—you’ll arrive at an accurate understanding of your truck’s rear differential configuration and be better prepared for maintenance, towing, and parts compatibility.
