What is the gear ratio for a 2005 Chevy 2500HD?

There isn't a single gear ratio for the 2005 Chevy Silverado 2500HD. The rear axle ratio varied by model and option, with common figures including 3.73:1 and 4.10:1, and some rare or special-order configurations pushing other ratios.

In this article, we break down how the gear ratio is determined on the 2005 2500HD, what the different options mean for performance and fuel economy, and how you can verify the exact ratio on your truck.

What determines the gear ratio on a 2005 2500HD

The gear ratio is set by the rear differential gear set (the axle). It interacts with the engine, transmission, drivetrain layout (2WD vs. 4WD), and whether the truck carries certain heavy-duty or towing packages. Because GM offered multiple axle options for the 2500HD in 2005, there isn’t a single universal figure for all trucks of this model year.

Common axle ratios used in 2005 models

These are the axle ratios most frequently found on 2005 Silverado 2500HD trucks. The exact ratio on a given vehicle depends on the specific build.

• 3.73:1


• 4.10:1


• 4.56:1 (rare, typically on certain heavy-duty configurations or special orders)

Knowing your exact ratio is important for towing, acceleration, and fuel economy calculations. If your truck isn’t configured with one of the more common ratios, consult your build documentation or contact a dealer with your VIN to confirm.

How to verify your exact ratio

To determine the precise gear ratio for your 2005 2500HD, use one of these reliable methods:

1. Check the rear axle tag on the differential housing. The tag usually displays the axle ratio (for example, “AXLE: 3.73” or “AXLE: 4.10”).


2. Review the original build sheet or window sticker. The axle ratio is often listed in the axle or drivetrain section of these documents.


3. Decode the VIN or use a GM/official build-lookup service. Entering the VIN into GM’s service tools or trusted third-party databases can reveal the original axle ratio and drivetrain options.


4. If you’re comfortable with mechanical work, you can count gear teeth (ring gear and pinion) to calculate the ratio. This requires removing the differential cover and is best done by a professional.

Knowing the exact ratio helps tailor towing setups, gear selection (where applicable), and fuel economy expectations for your specific truck.

Summary

The 2005 Chevy Silverado 2500HD did not use a single universal gear ratio. Most trucks used either 3.73:1 or 4.10:1 rear axles, with occasional rare configurations offering other ratios. To confirm the exact ratio on your vehicle, check the rear axle tag, review build documentation, or lookup the VIN in GM’s official records or trusted databases. This detail matters for towing performance and efficiency, so verifying it is worthwhile if you’re planning heavy-haul use or comparing fuel economy data.

How can you tell the difference between a 3.73 and a 4.10 gear ratio?

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

What is the rear end ratio of a 2005 Duramax?

All duramax trucks had 3.73 gears.

What is the gear ratio for a 2005 Chevy Silverado 2500hd?

3.73
Gear ratio 3.73. With 11.5 Ring Gear.

What is the gear ratio for a 2006 Chevy 2500hd rear end?

The 2006 Chevy 2500HD came with either 3.73 or 4.10 gear ratios depending on the specific configuration. The ratio is tied to the engine and drivetrain, with the Duramax diesel commonly equipped with 3.73 and the 6.0L gasoline engine often having 4.10. 
Determining your truck's gear ratio

• Check the RPO codes: The easiest way to be certain is to look up the RPO (Regular Production Option) codes on the sticker in your glove box. 
  • GT5: indicates a 4.10 gear ratio. 
  • There is no specific code for 3.73, so if you don't see GT5, it is likely 3.73, but checking the axle tag is a definitive way to be sure. 
• Consult your build sheet: The original build sheet for your vehicle will list the specific RPO codes.

Common ratios by engine

• Duramax diesel: Often came with the 3.73 ratio.
• 6.0L gasoline: Often came with the 4.10 ratio.