Free Shipping On Orders Over $49. Details

Talk to a Mustang Enthusiast
M-F 8:30A-11P, Sat-Sun 8:30A-9P
Win $15,000!! Enter Now
Coronavirus: We are Open For Business, Prioritizing health and safety Learn More

Eaton Limited Slip Differential; 31 Spline 8.8-Inch (11-14 V6; 86-14 V8, Excluding 13-14 GT500)

Item 21500
Call a Mustang Enthusiast at 1-877-887-1105
M-F 8:30A-11P, Sat-Sun 8:30A-9P
Market Price $622.99 You Save 12% ($71.80)
Our Price


FREE Shipping

Will this fit your Vehicle?

Select a different vehicle Help?
Update or Change Vehicle
In Stock

Ship to: Ashburn - 20149
Sorry, please enter a valid US or CA postal code
We're sorry, zip can't be updated at this time.
    Create a list
    Add to New List

    Saved - View your saved items

    We're sorry. We couldn't save this product at this time.

      Review & Installation Video

      Hey, guys. Today we're gonna be taking a look at the Eaton 31 Spline 8.8 Limited Slip Differential, for '86 to 2014 V8s and 2011 to 2014 V6 Mustangs. This is a Posi unit. It's gonna be a good option for the guys out there with an 8.8 rear that are looking to replace their diff with the next upgrade over stock and that want a performance-oriented name like Eaton. Eaton tends to be on the more expensive side, but it is a proven name in the aftermarket performance world. This diff costs about 550 bucks. It has carbon disks and it requires the use of 31 spline axles, which gives it that upgrade over the factory components. And if you're planning on, or already have some bigger power and torque numbers from your Mustang or the car sees track time or hard launches, a differential upgrade should be something that you're looking into. When it comes to the install, I'm gonna call it a full three out of three wrenches on the difficulty meter.If we take a step back for a minute and look at the need for a limited slip diff, I'd say that the point of a limited slip differential or LSD like this one here, is to allow both rear wheels to put power to the ground and give better traction to both rear wheels. So, the thought is if there's any type of open diff transfer or an uneven transfer of power and torque to one particular wheel over the other that'll create a useless wheel spin where the car loses its forward momentum, the LSD is designed to eliminate this spin. It will transfer the torque of both wheels evenly, which will have a few benefits in both street and track applications. This means a stable differential lock pattern that won't fail due to the upgraded components, no slipping, more durability, gentle transitions, and even a quiet operation.There are a couple of reasons to change or upgrade your differential. Maybe you've got a stock diff and it's just getting old and chattering or maybe you plan on hitting the drag strip and you've got some power that you'd like to cleanly get to the ground. Maybe you have a V6 and you're looking to upgrade to an 8.8 setup, and maybe you have a V6 that just needs a heartier rear diff. Either way, this Eaton diff would be a good option because it's got a balance of being an upgraded part that can handle more power and torque, but it isn't such an upgrade that it wouldn't make sense for a completely stock car to upgrade to. It's also user-friendly for streetcars. This diff is gonna require the use of 31 spline axles. So, if you've got an '04 and under V8, you're looking at upgrading your axle since those cars did come with factory 28 splines. If you've got an '05 and up, you can reuse your factory axles with this diff, but you are still looking at an upgrade due to the fact that this diff has carbon disks.The carbon fiber disks that I keep referencing to refers to the clutch pack. This diff uses the carbon friction plates because they're much more durable and they're designed for higher torque than the factory stock friction plates. This is gonna work for cars with both solid axle and IRS or independent rear suspension, and you will need to reuse or grab a new 8.8 rear gear set. This diff won't come with aftermarket rear gears. One other note would be the recommended use of 75W rear gear oil for street use since this will give me the same oil weight as factory. And you are gonna need 3 quarts and 4 ounces of friction modifier for the initial fill. For colder temps or for race use, you can try 75/140. This diff will not work for the '99 to '04 Cobra or the '13 to '14 GT500 either. So, just be aware of that.When it comes to the install, I said it earlier but this is gonna be a full three out of three wrenches in the difficulty meter. In a lot of cases, this will be a shop install but it's not impossible to do at home either.If you guys are interested in this Eaton LSD, you can always check it out more online right here at

      Product Information

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


      • Put the Power to the Pavement
      • Assembled 8.8" Limited Slip Differential
      • Includes Carbon Fiber Clutch Packs
      • Heavy Duty
      • Requires 31 Spline Axles
      • Fits 1986-2014 V8 and 2011-2014 V6 (Excludes 1999-2004 Cobra & 2013-2014 GT500)


      Limited Slip Differential. Is your stock rear end leaving you stuck in the lurch? Then you need to upgrade to a Eaton 8.8in 31 Spline Limited Slip Differential from AmericanMuscle. A Limited Slip Differential (LSD) sometimes referred to as a "Posi" will allow both rear wheels to put the power down on the pavement giving you better traction and more impressive burnouts.

      Heavy Duty. This Eaton Limited Slip Differential features a solid cast iron casing construction with a spring loaded pack and race-bred carbon fiber clutch packs. This helps the Eaton LSD deliver the highest performance even under stressful driving conditions. This LSD is virtually bullet proof and is exactly what you would expect from a name with a heritage like Eaton.

      Application. This Limited Slip Differential is the same original equipment used in the 2003-2004 SVT Cobra Mustang. It will fit both solid axle suspensions equipped V8 Mustangs from 1986 to 2014 and 2011 to 2014 V6 Mustangs. Requires 31 spline axles. (Will not fit the 1999-2004 Cobra and 2013-2014 GT500).

      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.

      Technical Note. You will need to reuse your factory 8.8” gear set, or upgrade to a set of our 8.8" rear gears required for this Limited Slip Differential. No aftermarket gears are included. For normal driving conditions we recommend you use 75W 90 rear gear oil. This will give you the same oil weight as factory. For colder temps or race use try 75w 140.

      Fitment: 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

      MPN# 19588-1

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (16)

      Write a Review

      Ratings Summary

      4.9 out of 5 overall rating from 16 customers

      Installation Time: Full Day

      Installation Cost: $500-$1000

      • November 18, 2018

        5 2006 GT - AnupS

        Great diff

        Very happy with this purchase. Had a loca shop install diff with new gears, new axle bearings, and new diff cover. Car feels much more stable. Even while tires are spinning, car goes forward in a straight line. Great purchase.

        Helpful (6)
      • June 18, 2018

        5 1993 LX - JeremyB Installation Time: Full Day

        Eaton posi

        Works great so far. I really like it better than the mini spool it was in my car.

        Helpful (6)
      • April 06, 2018

        5 2011 GT - Swaggyd Installation Time: Full Day


        Now this is amazing. Both wheels spin and hook hard. I never knew this could help your car go faster but it does. Bog bang for your buck. This has carbon fiber clutches so its really strong

        Helpful (5)
      • March 18, 2018

        5 2008 GT500 - Jarhead500 Installation Time: Afternoon

        Very nice

        Amazing difference in traction. My factory diff started slipping at the track. After getting it up on jack stands and testing the rear end, there is a night and day difference between the 2. The car launches much straighter and harder than it ever has. It will be nice to see the difference in my 60’ times. It was a toss up between the Easton and the Yukon. Both seemed to be a very nice part but the Eaton seemed to be the choice of most people. The Yukon seemed to have more negative reviews than the Eaton. I am pleased with this part but only time will tell on how good or bad it truly is.

        Helpful (8)
      • June 23, 2017

        5 2004 GT - CoryP Installation Time: Afternoon

        Eaton LSD

        This differential made a world of difference.. it's not call Eaton for no reason cause this bad boy EATS the street like a true track monster! Better control and no one wheel wonders period.

        Helpful (7)
      • May 20, 2016

        5 2011 V6 - Tang11 Installation Time: Shop Install Installation Cost: $1000+

        2011 Ford Mustang

        Well not mush to say, but the Eaton Differential works very good

        Helpful (6)
      • September 28, 2015

        4 1998 GT - Nickname Installation Time: Weekend

        I'll give a better review when it breaks.

        I put the Eaton unit in as a replacement for a failed ford racing unit. Also put in Moser 31 spline axles, ford racing 3:83 gears, and a ford racing aluminum driveshaft, with the Steeda diff cover to finish things off. Everything went in well and I'm still in the break in. There's no unusual noises or anything else out of the norm. I'll post an update when it breaks.

        Helpful (8)
      • August 22, 2014

        5 2007 GT - MNShelby Installation Time: Weekend

        Eaton Differential Install

        This was a very easy install and seems to have improved the performance of my Mustang some. Acceleration is straight and true with very little tire spin unless I really get on it.

        Helpful (5)
      • July 18, 2014

        5 1991 Other - cudalax205 Installation Time: Full Day

        strong and reliable

        Product is strong and reliable I have had zero issues with it

        Helpful (7)
      • June 13, 2014

        5 2011 GT - LOUISSIUOL Installation Time: Shop Install Installation Cost: $250-$500

        great limited slip

        this limited slip works just fine for me and my twin turbo 2011 GT at around 800hp and 800ftlbs.

        Helpful (8)

      Questions & Answers (5 answers)

      5 Top Rated Questions

      push button traction control what if any upgrades will i have to do to the "push button traction control". i want to also put 3.73 gears in. just dont want to mess anything up

      • No upgrades or modifications are required. Traction control is a system that actually operates through the rear brakes; during moments of wheel spin, the T/C system rapidly engages the rear brakes in order to slow down the wheels until traction has been regained. If you change your gears, make sure you get your car tuned.

      Helpful (5)

      I have one of these in my rear end and there seems to be about an 1/8 inch of play in and out for each axle shaft and a clunk going down the road that is definately coming from somewhere in the rotating assembly. Is this amount of play normal or might it need rebuilt/do they make a rebuild kit? I have no clue how old it is/the number of miles. The u joints/ driveshaft appear straight and in good shape.

      • The 8.8" rear should have approximately 1/8" of axle end play when properly set up. The noise may be a bearing issue, or a gear issue.

      Helpful (0)

      What gear oil does it require and any additive or anything

      • The Eaton Limited Slip Differential should run your stock weight gear oil to maintain proper lubrication of the ring and pinion gears. We do recommend a friction modifier as this is still a clutch type differential.

      Helpful (0)

      What is the difference with the 3.7 mustang differential to the limited slip differerential? I have 4.10 gears installed in my 2012 mustang 3.7, and wanted to know the difference between the stock differential for my car to this limited slip differential? Would it be beneficial to my car? If so, how?

      • If you already have limited slip no difference but if you have a standard differential. A limited slip will more regularly put power to both wheels you won't notice any difference unless you have wheelslip problems

      Helpful (0)

      Is this part required when upgrading from 2.73 factory gears to ford racing 4.10 gears? I want to upgrade my gears for faster acceleration and was just needing to know that when I purchase the gears, will I have to purchase the limited slip differential. I own a 2013 V6 Mustang with stock 2.73 gears. I want to upgrade to 4.10's. Thanks! Jeramie

      • No you don't need an upgraded differential. It would give you better grip to go with an upgraded diff., but its not required.

      Helpful (0) Show 3 more answers
      Post Your Question

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Limited Slip Differential

      Tech Specs

      • 8.8" Limited Slip Differential
      • Formula One race-bred carbon fiber clutch packs to limit wheel spin
      • Spring pre-load pack and cast iron case for a virtually bullet proof construction
      • Requires 31 spline axles
      • Requires 3 quarts Gear Oil
      • Requires 4 ounces of CM-19546-A1 friction modifier with initial fill
      • Fits solid or independent rear suspension

          Related Mustang Categories