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Alloy USA 8.8-Inch 5-Lug Axles; 31 Spline (05-09 GT, GT500)

Item 18958
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$259.99 (pair)

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      Review & Installation Video

      Hey, Justin with here, taking a closer look at the alloy USA 31 spline 8.8 axle kit, fitting all 2005 and newer GTs, all 2011 and newer V6's, and all 2007-2009 GT500s. Anyone who is hardcore into drag racing probably has a few stories to tell about experiencing a busted axle. The truth is the factory axles are fine for most but when you really start adding some horsepower and launching on a sticky tire, you run the risk of damaging or even breaking those factory axles. Speaking of which if you want to see us subject our project cars to a few quarter mile beat downs, you have to subscribe to our YouTube channel by clicking on the link below. This kit from Alloy comes with everything needed to eliminate those weak factory axles from the equation in your S197. The major players in this kit are the brand new 31 spline axles which have been made from a high quality alloy steel, using a unique heat treating process which basically just ensures a stronger, much more durable axle. Alloy then uses what's called a cold form, rolled spline process to process a spline that is roughly 35% stronger than a standard cut spline. Alloy stand behind this design so much that they include a 10 year warranty with every set of axles sold. If you want to hear more about what our customers are saying about using these axles in their own rides, you have to click the link below to head back to the product page at That kit does include the factory ABS sensors and even includes brand new wheel studs, bearings, and axle seals. Even though we always encourage our backyard mechanics to tackle almost any job, diving into the rear end and swapping axles can be a little tricky if you've never done it before, so that's why we recommend leaving this one in the hands of your local shop. On the other hand if you have no problem around the garage, just leave yourself about 4 hours from start to finish to get the job done. Either way if you have any questions about the fitment, the axles themselves, or about the install, don't hesitate to get in touch with one of our Mustang experts. So if you're serious about dragging your S197 and you want to eliminate the possibility of a busted axle altogether from the equation, then you might want to check out the Alloy 31 spline axle kit available right here at

      Product Information

      Features, Description, Reviews, Q&A, Specs & Installation


      • 1541H Alloy Steel
      • 31 Spline
      • 5 X 4.5" - Five Lug Design
      • 10 Year Warranty!
      • Driver and Passenger Side Axles Included
      • Fits 2005-2009 GT and 2007-2009 GT500 Mustangs with 8.8" Rears


      Performance Upgrade. If your Mustang is heavily modded or running a forced induction setup, your stock axles might be too weak to take the heat. These premium quality 1541H alloy steel axles will ensure that all the power and torque is transferred straight to the pavement - where it belongs.

      Stronger than OEM. Manufactured from high quality 1541H alloy steel using a computer controlled induction heat treatment that results in a stronger, more durable axle shaft. Alloy USA uses a cold-formed rolled spline process that produces an axle spline that is up to 35% stronger than standard cut splines.

      10 Year Warranty. These Alloy USA axles come with a 10 year limited warranty to be free of defects in material and workmanship from the date of purchase. Some limitations do apply. Please see the full Alloy USA Warranty disclosure for details.

      Application. This pair of Alloy USA 5-Lug 31 Spline Axles are specifically designed for use on 2005-2009 GT and 2007-2009 Shelby GT500 Mustangs that have the stock 8.8" 31-spline LSD installed.

      Application Note: 1986-2004 V8 Mustangs came factory equipped with 28 spline axles, except for 2003-2004 SVT Cobras which were 31 spline. All 2005 and newer V8 Mustangs come equipped with 31 spline axles.

      Fitment: 2005 2006 2007 2008 2009 Details

      MPN# 12189

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (16)

      Write a Review

      Ratings Summary

      3.8 out of 5 overall rating from 16 customers

      • November 10, 2019

        5 2007 GT - Lurch904

        Great quality

        Looks awesome rides smooth no noise Great for hard launches!!!

        Helpful (0)
      • September 10, 2017

        4 2009 GT - JamesT

        Packaged wrong.

        Disassembled rear diff to install. Wheel studs were installed in axles already when I found out that the axles were both the same length!!! Lost 2.5 quarts of Royal Purple lube and friction modifier. Now in process of contacting A/M for correct axles and new studs or refund. Always have had good luck with A/M so hopefully this can be resolved.

        Helpful (10)
      • September 05, 2017

        4 2007 GT - jptaguilar

        Alloy Axles

        I purchased these axles as I had a bent one on my car. The axles went in and fit perfectly, but as many had mentioned the wheel studs are a little too short. I wasn't going to use the new ones and then install the axles to then find out they are too short. I went ahead and used my originals. Have had the axles on for about a month now and they ride great. Overall a great purchase.

        Helpful (10)
      • April 28, 2016

        1 2009 GT500 - Justin

        Horrible replacements from stock

        My stock axles took several 6k rpm launches and finally bent and I chose these as replacements, decided to only launch at 3k rpm at the track and bent them within 10 launches... Horrible

        Helpful (11)
      • September 24, 2015

        5 2005 GT - Twill216


        Product was awesome. Packaged nicely, short and long side were marked. Removed old tone rings and they fit snug on the new axles. Overall awesome product. Recommend to anyone

        Helpful (11)
      • June 14, 2015

        3 2014 GT - Peter


        It was stressful trying to get the bolts on, although I had a proper mechanic do it I saw him struggling through the process.

        Helpful (12)
      • December 22, 2014

        5 2011 V6 - JasonK11

        Great Product

        I have had these axles on my car for 3 months now and they are great much firmer than stock if you are changing your gears out like I was you might as well change your axles while you got it all apart these are a perfect upgrade

        Helpful (11)
      • July 23, 2014

        1 2005 GT - Tesla8

        Poor machining and lousy bearing and seals

        Bought a set and had installed at a well respected shop. After install took it for a drive and it sounded horrible like bad bearing or similar. (picture driving on huge offroad tires sound) I drove an hour total before having it torn back apart to investigate. Turns out the axles have machining marks and are out of round because of it. The seals were leaking after 1 hour and the bearings were already looking bad. Everything ended up getting ripped out and replaced with stock again. AM had Great customer service though. I would not waste chancing $500 in labour installing and removing to find out they have similar issues. Spring for the Moslers.

        Helpful (11)
      • May 05, 2014

        5 2013 GT - deepimpactgt

        great axles

        These axles are a great upgrade for anyone planning on running drag radials. My car has the optional track package which comes with the boss 302 torsen differential so I ended up needing 3 bottles of gear oil(used royal purple), 2 bottles should be sufficient for a standard gt. I reused my old reluctor rings for the wheel speed sensors. It was fairly difficult to remove them from the stock axles, but a little heat and a big pry bar got the job done. The other major obstacle is installing the wheel studs which need to be pressed in. I used a hammer to pound them in instead of pressing. Not the ideal method but it was effective. Overall it was a fairly simple install that anyone with some mechanical ability can handle in their garage at home.

        Helpful (11)
      • April 03, 2014

        5 2011 GT - WhoWray

        Needed stronger axles.

        Not having to worry about a bent or broken axle is nice. Did upper control arm and new carbon fiber traction rebuild at the same time. So the rear end seems so solid. My 600+ HP will not go to waste. As always American Muscle has the best products and quick delivery.

        Helpful (11)

      Questions & Answers (5 answers)

      5 Top Rated Questions

      Are all of the components manufactured in the USA, to include bearings, seals and studs?

      • These pieces are sourced internationally.

      Helpful (0)

      Would these be compatible with a Torsen differential? T2 or T2R

      • As long as it is a 31 spline differential and 8.8" rear end, this should work with it.

      Helpful (0)

      compatible with 2008 V6? I am planning to upgrade by 7.5" V6 axle to 8.8". All the pre-assembled rear ones do not come with gears and differential locks that I am planning to put on for my racing. So can I use this kit along with gears and limited slip differentials for 8.8" to complete the upgrade? What else would I need?

      • Yes the axles would work with a 8.8" housing you would just need to purchase a Limited Slip Diff that supports 31 splines and some 8.8" gears like 4.10 or 3.93 etc. You can get everything you need from AmericanMuscle

      Helpful (0)

      About these axle replacements I want to know if these axles would be compatible with an auto trans

      • Yes, they will work with a manual and automatic.

      Helpful (0) Show 1 more answer

      ABS? Can the factory ABS sensors be relocated to these axles?

      • Yes, in fact that is what I did. It's not easy but it can be done. You need to heat up the rings with a torch then pry them off while being careful not to damage the teeth. To install them on the new axles I put the rings in my oven then hammered them on the axles with a brass punch.

      Helpful (0) Show 2 more answers
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      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (2) 31 Spline Axles
      • (10) Wheel Studs
      • (2) Outer Axle Shaft Bearings
      • (2) Seals

      Tech Specs

      • Splines: 31
      • Length: 31.688" / 32.813"
      • Type: C-clip
      • Stud Pattern: 5 x 4.5"
      • Stud Type: Press in

      Will It Fit My Mustang

      • Bullitt - 08, 09
      • GT - 05, 06, 07, 08, 09
      • GT500 - 07, 08, 09

      Fits 8.8" rear gears with 31 spline LSD or Spool only

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