How do I identify my rear axle?

Per the document, you need three measurements from your rear end assembly: 1. Outside bearing diameter, 2. Housing flange, and 3. Stud pattern and bolt circle on the axle flange. Compare these to the dimensioned flange diagrams shown.

Can I identify my axle just by how it looks compared to the diagrams?

No. The document warns that your rear end may differ in appearance from the diagrams and says to rely on the measurements to be certain. It also notes custom rear ends may use bearings and flange patterns different from original equipment.

What is the housing flange dimension shown for the 8.8" Ford?

The 8.8" Ford diagram shows dimensions including 3.362, 2.840 DIA, 3.150, and 1.680 inches.

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Rear Axle Housing Flange ID Chart - Ford 8.8, 9", Mopar, Chevy 12 Bolt, Dana 60

Rear axle identification chart showing dimensioned bearing and flange bolt patterns for various rear ends

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Rear axle identification chart with dimensioned flange bolt-circle patterns for Ford, Chevy, Mopar and other rear ends to identify the assembly.

AI caption June 2013 · Photo 983 of 1095

This document is a rear axle identification reference chart. It instructs readers on how to correctly identify a rear end assembly using three key measurements: outside bearing diameter, housing flange dimensions, and the stud pattern/bolt circle on the axle flange. It cautions that custom rear ends may use axle bearings and housing flange patterns different from original equipment, and that the actual rear end may differ in appearance from the diagrams, so measurements should be relied upon for certainty. The chart presents ten labeled housing-end flange diagrams with dimensional callouts (in inches): Small Ford, Big Ford, Big Ford (New Style), 8.8" Ford, Chevy (Special), 8-3/4 and 9-3/4 Mopar / Dana 60, Olds/Pontiac, 8-1/4 and 9-1/4 Mopar, Mark Williams, and 12 Bolt Chevy, plus an axle flange cross-section diagram showing offset. Each diagram shows bolt hole positions, flange outline shapes, and diameters such as bearing bore diameter (commonly 3.150 DIA) and bolt spacing dimensions. A reader can use this chart to compare measured dimensions from their own axle housing ends against these known factory patterns to determine which manufacturer's rear axle they have, which is useful when sourcing axles, bearings, retainer plates, or brake backing plates.

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Frequently asked questions

How do I identify my rear axle?: Per the document, you need three measurements from your rear end assembly: 1. Outside bearing diameter, 2. Housing flange, and 3. Stud pattern and bolt circle on the axle flange. Compare these to the dimensioned flange diagrams shown.
Which rear axle types does this chart cover?: Small Ford, Big Ford, Big Ford (New Style), 8.8" Ford, Chevy (Special), 8-3/4 and 9-3/4 Mopar / Dana 60, Olds/Pontiac, 8-1/4 and 9-1/4 Mopar, Mark Williams, and 12 Bolt Chevy, plus an axle flange cross-section showing offset.
Can I identify my axle just by how it looks compared to the diagrams?: No. The document warns that your rear end may differ in appearance from the diagrams and says to rely on the measurements to be certain. It also notes custom rear ends may use bearings and flange patterns different from original equipment.
What is the housing flange dimension shown for the 8.8" Ford?: The 8.8" Ford diagram shows dimensions including 3.362, 2.840 DIA, 3.150, and 1.680 inches.