Differential Identification Guide | West Coast Differentials (2024)

Accurate Differential Identification is the first and most important step in your differential repair, upgrade or overhaul project.

The following information is provided to help you identify the differential you are working on. If in doubt, consult one of our differential experts at (800)510-0950! Professional technical support is available Monday thru Friday from 8am to 5pm Pacific Standard Time.

The most accurate differential identification is provided by the bottom line of the tag number or axle tube stamp. Differential tags can easily be used to identify Dana and Ford differentials.

The Bill of Material (BOM) number is used to identify Dana differentials. The BOM will identify the model number, the gear ratio, the type of differential, and all component parts. Traditional BOM’s are 6 digits followed by 1 or 2 digits and start with the numbers 60 or 61. On some tags, the first 2 digits don’t appear on the tag, but they must be used to identify the axle. For instance, you might see 5561-1 for the BOM, but the 60 has been dropped, and one would need to use 605561-1. Later BOM’s may start with the first 3 digits of 200, but these are typically not dropped from the tag.

*** The B.O.M. Numbers stamped into the long tube of the axle housing are often faint and hard to read. Using a metal scraper will typically reveal the numbers most easily. Cleaning with a wire wheel is not recommended as it usually makes the numbers harder to see ***

The “Dana Expert” website is no longer available. However, the Dana Aftermarket Media Library can be used to identify all aspects of a particular axle using the Bill Of Materials number.

1. Navigate to the Dana Aftermarket Media Library
2. Enter the BOM number in the Keyword Search field (top left corner of the page).
3. Click on the resulting literature link
4. Search within the document by clicking on the Magnifying Glass at the top, or by simply using “Control-F” and re-entering the BOM number.

Need help identifying your differential or not sure which replacement or performance parts you need? Call our staff of differential experts at (800)510-0950. We’re here to help Monday thru Friday from 8AM to 5PM PST

Ford differential tags are very straightforward, as indicated above. The Month of Manufacture uses the following format:
A = January, B = February, C = March, etc.

GM Vehicles come with a RPO code tag, usually located in the vehicles glovebox or door jamb. These tags have a wealth of information about your specific vehicle’s equipment and specifications. Read more about GM RPO Axle Identification Codes

Need help identifying your differential or not sure which replacement or performance parts you need? Call our staff of differential experts at (800)510-0950. We’re here to help Monday thru Friday from 8AM to 5PM PST

Not sure what the part you need is called? Our Online Catalog has Exploded View Diagrams for nearly every Axle Assembly that we service. You can also use our Generic Exploded View Diagrams to identify the part you want by name. This way we’ll be on the same page when you call!

Without an ID tag, differentials are identified by the number of cover bolts, the distinctive shape of the cover, the number of ring gear bolts, and ring gear diameter. They can also be identified by whether the center section is an integral or dropout design. Dropout differentials are also referred to as 3rd members or pumpkins.

Use the images below to Help Identify Your Differential.

Our full-time staff of LIVE Differential and Axle Parts Experts are ready to help you Monday thru Friday from 8AM to 5 PM Pacific Standard Time.

Differentials are all we do….Let us take the guesswork out of your project!

(800) 510-0950