Differential Identification

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.

On this page:  Differential Identification by Tag Number  |  Visual Differential Identification

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.

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Differential Identification by Tag Number

Dana Spicer Differential Tags

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 BOM may be used with the Dana Expert to identify all aspects of this particular axle. Make sure to select the appropriate Light Duty or Heavy Duty section of The Expert.

On GM axles made by Dana, the Bill of Material is usually stamped in the right hand tube underneath the spring. These BOM’s normally start with 60, and the first 2 digits are not typically dropped as in some cases with Dana ID tags.

Ford Differential Tags

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 RPO Identification Codes

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.

 

 

For complete listings of the Differential Parts available for your application, View or Download the West Coast Differentials Catalog. We have a huge inventory and orders placed by 4PM Pacific Standard Time can usually ship out the same day!

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.

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Visual Differential Identification

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. The chart below shows various differential covers and 3rd Members.

 

 

Differential Component Identification

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