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Notice! Fulfillment staff will be off site 9/30-10/6. Orders will be processed the following week of 10/9/23. Please excuse any delays.
Notice! Fulfillment staff will be off site 9/30-10/6. Orders will be processed the following week of 10/9/23. Please excuse any delays.

9.25 IFS AAM Rebuilt Front Differential

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***Current lead time on front differentials is 3 weeks from order to shipping. We intend to stock these in the near future. ***

The AAM 9.25 IFS axle was used in GM K-series trucks from 1988-2010. It features a lightweight cast aluminum housing and has 33 spline axle shafts. Gearing available over the years ranges from 3.42 to 4.56. It is a very durable front differential, widely available, and is relatively easy to work on/with. It features an electronic locking mechanism that can be activated easily by a transfer case switch. 

You will find 3.42-4.56 gearing in the years 1988-2000, and then 3.73 and 4.10 only from then on. Later model cases years 2009/2010 have a slightly lower profile casting and fit better in tight spaces such as Duramax conversions and 6.6 gasoline-powered vans. 

Timberline now offers rebuilt units for van builders with the following details
-Case inspected, dismantled, solvent-based heated cleaning, smoothed and painted with high build grey paint. Differential comes pre-trimmed/shaved for clearance around tight spots of the mounting location. (no significant structural compromise/performance degradation)
-Replacement of hard parts showing any signs of wear or potential failure
-Replacement of gaskets, seals, and bearings with OE quality parts and Timken/Koyo bearings
-Replacement of mounting bushings with GM/ACDelco OE parts
-Replacement of locking motor with AAM OE unit (wiring pigtail not included)
-Gear ratios available 3.42, 3.73, 4.10 and 4.56

Note: Units are rebuilt with remanufactured cases. Cases may show small pockmarks, imperfections, and chips. We do our best to make cases attractive and more importantly reliable, but cosmetic imperfections may be present. 

Fitment notes: Timberline will soon be offering 8.25 AAM carriers and mounting solutions which fit much better in some models, including the 6.6 Duramax and 6.6 gas vans. 2021+ gas vans will accept the 9.25 front diff using our 5" lift design only, however it does require additional fabrication and careful fitment. 


Fitment Designed for: 

Van Side -
2003-2020 Chevrolet Express 2500/3500/4500 series vans 4.8L and 6.0L
2017-2022 4.3/2.8 vans with 5" lift only
2003-2017 6.6 Duramax diesel vans with 5" lift only
2021-2022 6.6 Gas-powered vans with 5" lift only (requires additional fab/trimming/fitment)

Tools Required:

Unit requires hand tools only to mount, our front diff mounting solutions require additional tools. 


Differential with new lockout motor. 

Tips / Skill Level:

1-10 (10 being most difficult) Level 3

This product may work with other model vehicles. 

Shipping, Fulfillment, Taxes, Quality, and Returns

  • Shipping: Our components are carefully wrapped and packaged and ship UPS, USPS, or FedEx, depending on what is available. If you require a particular carrier, please contact us ahead of your purchase.  Customers in Colorado may arrange for in-person pickup within 1-2 business days of purchase taking noted lead times into consideration. 
  • Shipping/Fulfillment time for components: We typically ship within 1-2 business days of your order and we carefully monitor our inventory. In the event that we are unable to meet that timeframe, we will contact you and arrange either a full refund or a timeframe for fulfillment agreeable to the customer. 
  • Taxes: Colorado residents must pay sales tax of 7.5%, no sales tax is collected on out-of-state shipments currently. 
  • Quality and Returns: We are consistently complimented on the quality of our products and the ease of install. Components are hand-built here almost exclusively in Colorado by seasoned professionals who are fanatics about design and execution. If you are in any way disappointed in the components we will issue a full refund less the cost of shipping when the product is returned. If you decide to return any components that didn't apply to your build or you changed your mind about, shipping and a 15% restocking fee will be deducted from the purchase refund.