How to find gear ratio on 2004 Silverado?

The gear ratio on a 2004 Silverado is shown on the rear axle tag or on the vehicle’s placards, and you can confirm it by counting the ring and pinion teeth if the tag is unreadable. The most common rear-axle ratios for this era are 3.42, 3.73 and 4.10, with exact figures depending on engine, transmission and model configuration.

Where to look for the axle ratio

Before diving into the measurement, it helps to know the safest and quickest sources to check first. The following locations commonly display the axle ratio for a 2004 Silverado.

• Rear differential tag: Look for a small metal tag on the differential cover or a stamped mark on the cover itself. It often reads “AXLE” or “RATIO” followed by a number (for example, 3.73 or 4.10).


• Differential cover stamping: If there’s no tag, some axles have the ratio stamped directly into the diff cover or the cover surface. Clean the area if needed to read the number clearly.


• Vehicle placards: Check the driver’s door jamb sticker and, on some models, the glove box SPID (Service Parts Identification) label for an “AXLE” or “Axle Ratio” entry.

These sources are the quickest way to confirm the ratio without disassembly. If you can read any of these labels clearly, you’ll have your answer in minutes.

Reading the placards and RPO codes

In addition to the diff tag, GM often encodes the axle ratio on vehicle documentation and labels. Decoding these can be straightforward if you know where to look.

• Door jamb sticker: Locate the label on the driver’s door frame; look for a line labeled “AXLE” or similar, which lists the rear axle ratio in numbers (e.g., 3.73).


• Glove box SPID label: Open the glove box and read the SPID label for an “AXLE” entry. The value shown is the axle ratio or a code that maps to a ratio.


• VIN-based lookup: If the physical labels aren’t legible, you can use the vehicle’s VIN to query a GM VIN decoder or contact a dealer. They can translate the VIN-encoded options to the actual axle ratio for that vehicle.

Using these placards and codes often yields a quick, non-destructive way to confirm the gear ratio without removing any parts.

Manual check: counting teeth

If the tags or placards aren’t accessible or readable, a hands-on method will confirm the ratio. This requires removing the differential cover.

• Prepare safely: Lift and support the truck, place a drain pan under the differential, and wear eye protection and gloves. Release the differential fluid.


• Access the ring gear: Remove the differential cover to expose the ring gear and pinion gear.


• Count teeth: Count the number of teeth on the ring gear (the large gear) and on the pinion gear (the smaller gear). The axle ratio is calculated as Ring Teeth ÷ Pinion Teeth.


• Verify and reinstall: Use the calculated ratio to confirm compatibility with your drivetrain. Clean, reseal, and reinstall the differential cover with proper torque on the bolts and refill the differential with gear oil.

This method provides a definitive result, but it should be performed only if you’re comfortable with basic mechanical work. If you’re unsure, have a professional perform the inspection and measurement.

Why the axle ratio matters

The axle ratio affects performance in several ways: acceleration, towing capability, fuel economy, and engine RPM at highway speeds. For example, a lower numerical ratio (like 3.42) generally yields better top speed and fuel economy, while a higher ratio (like 4.10) improves torque for towing and heavy loads but increases engine RPM and fuel consumption at highway speeds.

Common considerations for 2004 Silverado owners

Model differences (1500 vs. 2500 HD), transmission type (manual vs. automatic), and drivetrain configuration (2WD vs. 4WD) can influence available axle ratios. When upgrading gears or selecting a used vehicle, confirm the exact ratio for your specific build to avoid drivetrain mismatches.

Summary

To determine the gear ratio on a 2004 Silverado, start with the rear differential tag or the vehicle placards (door jamb or glove box SPID). If those aren’t legible, use a VIN decoder or dealer lookup. As a last resort, you can count the teeth on the ring gear and pinion gear after removing the differential cover. Knowing the correct ratio helps optimize towing capabilities, performance, and fuel economy for your truck.

How do you tell if you have 3.73 or 4.10 gears?

You can tell if you have 3.73 or 4.10 gears by manually counting, checking the differential cover for a tag, or finding the ratio stamped on the ring gear. The most direct method is to lift the rear wheels, rotate one tire one full revolution, and count how many times the driveshaft turns; 3.75 turns indicates 3.73 gears, while slightly over 4 turns indicates 4.10 gears.
 
This video demonstrates how to check your gear ratio by counting the driveshaft turns: 48sBent Motorsports OffroadYouTube · Sep 22, 2023
Method 1: Manual count (with the vehicle jacked up)

1. Jack up the vehicle: Safely lift the rear of your vehicle and secure it on jack stands. Ensure the wheels are off the ground. 
2. Mark the driveshaft and a tire: Place a mark on one of the rear tires and a corresponding mark on the driveshaft. 
3. Rotate the tire: Rotate the marked tire forward one full revolution. For an open differential, you may need to lift only one wheel and have someone hold the other stationary, or lift both wheels and rotate one tire twice while the other tire is on the ground. For a locked differential, lift both rear wheels and have one tire rotate once while the other rotates once in the opposite direction. 
4. Count the driveshaft turns: Count how many times the mark on the driveshaft has rotated. 
   • 3.73 gears: The driveshaft will turn approximately 3.753.753.75 times for one full tire revolution. 
   • 4.10 gears: The driveshaft will turn a little over 444 times for one full tire revolution. 

Method 2: Check the differential cover tag 

1. Locate the tag: Look for a small metal tag that is usually bolted to the differential cover. It may be on one of the bolts. 
2. Read the ratio: If the tag is still present, the gear ratio will be stamped on it. It will likely be a number like "3.73" or "4.10". 

You can watch this video to learn how to find the differential cover tag: 51sFlawed OffroadYouTube · Apr 18, 2022
Method 3: Read the ring gear stamps 

1. Locate the ring gear: This requires removing the differential cover to get a clear view of the ring gear.
2. Find the numbers: Look for two numbers stamped on the teeth of the ring gear, such as "41" and "11". 
3. Divide the numbers: Divide the larger number (teeth on the ring gear) by the smaller number (teeth on the pinion gear). 
   • 41÷11≈3.7341 divided by 11 is approximately equal to 3.7341÷11≈3.73 
   • 41÷10=4.1041 divided by 10 equals 4.1041÷10=4.10 

This video shows how to read the ring gear stamps to find the gear ratio: 46sJL LIFE OFFROADYouTube · Nov 18, 2022

Can I find my gear ratio with my VIN?

You may be able to tell the gear ratio from a vehicle's VIN by using an online VIN decoder, though not all manufacturers include this information in the VIN itself. If the gear ratio is included, it will likely be in the Vehicle Descriptor Section (VDS), which are the 4th through 8th digits of the VIN. For many vehicles, a sticker on the driver's side door jamb or on the vehicle's build sheet or owner's manual is a more reliable way to find the gear ratio. 
How to check the VIN

• Use an online VIN decoder: Enter the full VIN into a free online decoder. Some manufacturers have their own decoders, such as Mopar's decoder. 
• Look for the gear ratio code: Some VINs will have a code within the VDS that represents the gear ratio (e.g., "3731"). 
• Consult the manufacturer: If the VIN decoder doesn't provide the information, contact the vehicle manufacturer for assistance. 

Other methods to find the gear ratio

• Check the vehicle sticker: Look for a sticker on the driver's side door jamb or on the vehicle's build sheet. This sticker often contains detailed information about the vehicle's equipment, including the axle ratio. 
• Look at the differential: Some differentials have a metal tag with the gear ratio stamped on them, or there may be a sticker on the axle itself. 
• Consult your owner's manual: The owner's manual or other paperwork from the vehicle's purchase often lists the gear ratio. 

How do I find out what gear ratio my Silverado has?

Identify your GMC or Chevrolet rear end gear ratio by the RPO Codes, usually located on the placard labeled “Service Parts Identification” inside the drivers door panel or glove box. Note that using the RPO code for parts identification assumes that the rear end has not been previously modified!!

What gear ratio does a 2004 Chevy Silverado have?

The 2004 Silverado gear ratio varies by trim and options, but common ratios are 3.42, 3.73, and 4.10. To find your specific ratio, check for the RPO code on the glove box sticker (e.g., GU6 for 3.42, GT4 for 3.73) or use a VIN lookup.
 
This video explains how to find your truck's gear ratio from the RPO code: 56sTattsForLifeYouTube · Sep 7, 2018
How to find your truck's gear ratio

• Look for the RPO code: The most reliable way is to check the sticker in your glove box. 
  • GU6: 3.42 
  • GT4: 3.73 
  • GT5: 4.10 
• Check the vehicle's documentation: The original owner's manual or dealer invoice may list the RPO codes.
• Use a VIN lookup: Input your Vehicle Identification Number into a VIN decoder to find the factory-installed options, including the gear ratio. 

This video shows how to find the RPO code on your truck's glove box sticker: 56swtbm123YouTube · Dec 17, 2014
Common gear ratios and their implications

• 3.42: A common and balanced ratio for a mix of fuel economy and performance. 
• 3.73: Offers more torque, improving towing and hauling capabilities, but with a slight decrease in fuel economy. 
• 4.10: Provides the most torque for heavy-duty towing, but results in the lowest fuel economy.