Differential Identification

By February 25, 2015Drive Train
How to Identify Your Differential

The first step to repairing or upgrading your differential is to correctly identify it. The best way to do that is to read the bottom line of the tag number or axle tube stamp.

Differential Identification by Tag Number

Differential tags can easily be used to identify Dana and Ford differentials.

Dana Spicer Tags

Dana Differential Tag Example

Look for The Bill of Material (BOM) number on the tag. It will identify the model number, gear ratio, 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 you’d 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 Dana website has a great search tool called The Expert where you can enter your BOM and get all aspects of your particular axle.

GM Axles BOM

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 Tags

Ford Differential ID Tag

Ford differential tags are pretty straightforward. The only piece of information you have to decode is The Month of Manufacture. It’s usually represented with a single digit number, a single letter, and a two digit number such as 6F17. The first number refers to the last digit of the most recent year prior to the model year of the vehicle. Therefore, for a 2007 model year, the axle was manufactured in 2006. The letter refers to the month: “A” for January; “B” for February and all the way through “L” for December. So the “F” in this example represents June. The last two digits refer to the day of manufacture. An axle with a date tag of “6F17” for a 2007 model year car was manufactured on June 17, 2006.

GM RPO Codes

GM RPO Code Tag

GM vehicles come with a RPO (Regular Production Option) code tag that contains lots of information. It’s usually located in the glove box or door jamb. Look for the area labeled “Service Parts Identification” and the prefix is usually F, G or H when referring to axle identification.

Differential Identification by Cover/Number of Bolts

If the ID tag or stamp is missing or unreadable, differentials can be 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 third members or pumpkins.

AAM 9.25″ Chrysler Front

AAM 9.25" Chrystler Front

AAM 10.5″ Chrysler

AAM 10.5" Chrysler

AAM 11.5″ GM/Chrysler

AAM 11.5" GM/Chrysler

AMC Model 20

AMC Model 20

AMC Model 35

AMC Model 35

Chrysler 7.25″

Chrysler 7.25"

Chrysler 8″ IFS Front

Chrysler 8" IFS Front

Chrysler 8.25″

Chrysler 8.25"

Chrysler 8.75″

Chrysler 8.75"

Chrysler 9.25″

Chrysler 9.25"

Dana 28 IFS

Dana 28 IFS

Dana 30

Dana 30

Dana 44

Dana 44

Dana 50

Dana 50

Dana 60

Dana 60

Dana 70

Dana 70

Dana 80

Dana 80

Dana S110 Third Member

Dana S110 Third Member

Ford 7.5″

Ford 7.5"

Ford 8″ Third Member

Ford 8" Third Member

Ford 8.8″

Ford 8.8"

Ford 9″ Third Member

Ford 9" Third Member

Ford 9.75″

Ford 9.75"

Ford 10.25″ & 10.5″

Ford 10.25" & 10.5"

GM ’55 Passenger Third Member

GM '55 Passenger Third Member

GM ’55 Truck Third Member Dropout

GM '55 Truck Third Member Dropout

GM 7.25″ IFS Clamshell

GM 7.25" IFS Clamshell

GM 7.5″ & 7.625″

GM 7.5" & 7.625"

GM 8″

GM 8"

GM 8.2″

GM 8.2

GM 8.2″ B.O.P.

GM 8.2" BOP

GM 8.25″ IFS

GM 8.25" IFS

GM 8.5″

GM 8.5"

GM 8.6″

GM 8.6"

GM 12-Bolt Passenger

GM 12 Bolt Passenger

GM 12-Bolt Truck

GM 12 Bolt Truck

GM 9.25″ IFS Clamshell

GM 9.25" IFS Clamshell

GM 9.5″

GM 9.5"

GM 10.5″ 14-Bolt

GM 10.5" 14-Bolt

Toyota Landcruiser

Toyota Landcruiser

Toyota 7.5″ Early Third Member

Toyota 7.5" Early 3rd Member

Toyota 8″ Third Member

Toyota 8" 3rd Member

Toyota Landcruiser 8″ Third Member

Toyota Landcruiser 8" Third Member

Toyota Landcruiser 9.5″ Third Member

Toyota Landcruiser 9.5" Third Member

Toyota 7.5″ IFS Clamshell

Toyota 7.5" IFS Front Clamshell

Toyota Tacoma/T100 8″ Third Member

Toyota Tacoma/T100 8" Third Member

Toyota Landcruiser 8″ Reverse IFS

Toyota Landcruiser 8" Reverse IFS Front

Toyota Tundra 8.75″ IFS

Toyota Tundra 8.75" IFS Front

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