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

Item 21500
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      Video Review & Installation

      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.



      Eaton 19588-1

      CA Residents: WARNING: Cancer and Reproductive Harm -

      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

      Customer Reviews (17)

        Questions & Answers

        10 More Questions

        Will It Fit My Mustang

        • Boss 302 - 12, 13
        • Bullitt - 01, 08, 09
        • Cobra - 93, 94, 95, 96, 97, 98, 99, 01, 03, 04
        • Cobra R - 93, 95, 00
        • GT - 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12, 13, 14
        • GT500 - 07, 08, 09, 10, 11, 12
        • LX - 87, 88, 89, 90, 91, 92, 93
        • Mach 1 - 03, 04
        • Other - 86
        • V6 - 11, 12, 13, 14

        Fits Mustangs equipped with a 8.8" rear end. Will not fit 1999-2004 Cobra and 2013-2014 GT500,

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