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Update 12/16 - Massive Site Update Coming January w/ tons of New Products, Current Inventory GM/Ford Kits ship in January, Thank you!
Update 12/16 - Massive Site Update Coming January w/ tons of New Products, Current Inventory GM/Ford Kits ship in January, Thank you!

Differential Mount System (standard) for 9.25 IFS 4x4 GM Van Conversion


This kit contains all the necessary components to mount a 9.25 IFS GM front differential from a 3/4 or 1 ton Silverado years 1999.5 to 2010 to an Express or Savana 2500 or 3500 series van years 2003-2021 with either the 4L80 or 6L90 transmission specifically. It will also work with the 8L90 variant but requires our custom motor mounts either for the 4.3 V6 or 2.8 diesel. 

This is the most complex part of the IFS GM conversion but we have developed a straightforward and easily repeatable means of completing the procedure, complete with template cutouts for the frame extension mods that have to be made, step-by-step instructions with lots of photographs on how the cuts should look, and a comprehensive set of hardware and brackets that only fit together one way. 

If you're a DIY builder building a Coilover van, a lowered AWD hotrod van, or any number of the other odd calls we routinely get, this is the one kit that will keep you from pulling your hair out over the build. 

This version of the kit is used for standard conversions where the van is lifted 0-3 inches. For vans with more lift, visit the Lifted version which includes drop bracket carriages to lower the entire assembly 4". 

NOTE: This system will interface with other popular brands of 4x4 conversions. If you are trying to replace a specific similar component seen in this kit for your other brand of 4x4, please contact us for more information. 

6.0 motor mount brackets can be trimmed while still in the vehicle. We offer pre-cut motor mounts for the 6.0 for the cleanest install if you prefer, though it is not necessary. 

Fitment Designed for: 

Van Side - 2003-2021 Chevrolet Express 2500/3500/4500 series vans with 4L80 and 6L90 Transmission (4.8L, 6.0L, 6.6L). (8L90 transmission requires Timberline 8L90 motor mounts)

Tools Required:

Standard hand tools, pneumatic tools, and torque wrench recommended, requires welding, cutting time significantly improved with a plasma cutter and undercoat removal facilitated with an acetylene torch or propane. This kit requires a small cut to the passenger side diff footer for clearance, as well as some trimming/grinding to the differential cooling fins for proper fitment. 


Timberline front cross-member, left plate, right differential support with bushing assembly, makeup plate, upper bracket, Timberline center link, all appropriate hardware, frame extension trim templates, printed color installation manual. Pre-cut motor mounts are available at additional cost.

Construction Notes:

1/4", 3/16" material CNC cut A36 mild steel, serviceable motor isolator sleeved bushings, grade 10 and grade 8 hardware, powder-coat

Tips / Skill Level:

1-10 (10 being most difficult) Level 8

This product may work with other model vehicles. 

It is a tight fit! It should be, this keeps the differential tucked up and out of the way, giving you the best ground clearance possible up front without requiring a large vehicle lift or compromising drivability. 

The 9.25 IFS differential should be the same in all 2500/3500 trucks years 1999.5 to 2010, though we have never built one with a differential earlier than 2005. The available gear ratios from built were 3.73 and 4.10. Most gas vans are 3.42 ratio. We offer a reverse 3.42 ring and pinion gear for regears. We also offer 3.73 and 4.10 gear options for rear differentials. If you are going up in tire size, this can often be a better solution. 

You can find diffs on used. The most common service step is to replace the axle shaft seals, other than that, they're pretty bomb-proof. 

Lastly, the 6.6 Duramax oil pan fits extremely tightly with this kit and requires further modification to the differential fins/trimming. Our 4" drop kit alleviates that, however, it is only recommended for lifted vans. 

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. 
  • 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.