Win A 2018 RTR Spec 3 Mustang Enter Now!
Talk to a Mustang Expert
Mon - Sun, 8:30 AM EST - 11:00 PM EST

Free Shipping On Orders Over $49. Details

Ford Performance Traction - LOK Limited Slip IRS Differential - 34 Spline 8.8 in. (15-18 GT)

Market Price $203.99 You Save 12% ($25.02)
Our Price

$178.97 (each)

FREE Shipping
  • Item 388769
  • MPN# M-4204-M

In Stock Ships same business day.
Ship to: ASHBURN - 20146
Please enter a valid Postal Code
We're sorry, zip can't be updated at this time.
Choose options to add to cart
    Create a list
    Add to New List

    Saved - View your saved items

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

    Features & Details

    • Put the Power to the Pavement
    • 8.8" IRS Limited Slip Differential
    • Factory OEM Replacement
    • Genuine Ford Racing Part M-4204-M
    • Requires 34 Spline Axles
    • Designed for Use with 3.31, 3.55 & 3.73 Super 8.8" Gear Sets
    • Fits 2015-2018 GT Mustangs
    Limited Slip Differential. This Ford Racing 8.8" 34 Spline Traction-LOK Limited Slip Differential is a direct fit replacement for your IRS equipped S550 Mustang GT. 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.

    Recommended Upgrade. This Ford Racing Traction LOK Limited Slip IRS Differential was specifically engineered for use with Ford Racing Super 8.8" IRS Gear and Pinion Sets, including 3.31, 3.55 and 3.73 gear ratios. Sold separately. Not for use with 3.15 gears.

    Application. This Ford Racing 8.8" Limited Slip Differential is the same original equipment that came standard on 2015-2018 GT Mustangs. It is designed for use with independent rear suspensions (IRS) and requires the use of 34 spline axles.

    Technical Note. This Limited Slip Differential requires 4-ounces of CM-19546-A1 friction modifier with initial fill, it is recommended to use differential installation kit M4210B3.

    Fitment: 2015 2016 2017 2018 Details

    What's in the Box
    • (1) IRS Limited Slip Differential
    Installation Info
    Will it fit my Mustang?
    • GT - 15, 16, 17, 18

    People Who Bought This Item Also Bought

    Customer Photos

    You Might Also Like

    8 Questions / 5 Answers

    Ask a Question

    I have a base model 2016 GT is this all I require to swap my gears from 3.15 to 3.55?


    • Hey Arturo, This differential is actually designed to work with steeper gears it isn't gears themselves. To upgrade to a 3.55 gear for your 15gt you would need item# 389949 which are not only the gears but the differential housing and differential to complete the entire install. Now if you wanted to you could get the ring and pinion separate, item#384402 but you would at least need one of these Ford differentials M-4204-MT or M-4204-M in order to complete the installation. And if you plan on making your mustang a high mileage car you would need a bearing a seals kits with the ring and pinion.


    Helpful (1)

    Hey I have a 15 gt 6speed and I think my differential is getting bad it has play in it and bump every Time i let off the clutch. So I'm going to change this out and see . Will this work with my car with 3:31 in it and is it a straight forward install


    Hi I think I have a worsen in my car - can I straight swap it for this one? thanks


    • The Ford Performance Traction - LOK Limited Slip IRS Differential will be a direct fit replacement for all 15-17 Mustangs with a 34 spline 8.8 rear, including those equipped with Torsen differentials.

      Rob D

    Helpful (0)

    Will this fit on my 2017 f150 with the 8.8 34 spline rear end


    • The Ford Performance Traction - LOK Limited Slip IRS Differential is specifically designed to work with the 2015-17 Mustang GT's and will not work properly with your 2017 F-150.


    Helpful (0)

    Will this work on a mustang ecoboost that's gonna be converted to 3.55's.


    • Yes, this works with 3.31, 3.55 & 3.73 gears.


    Helpful (0)

    Will this work for ecoboost with 3.31?


    • Unfortunately this will not work on an Ecoboost with the 3.31.


    Helpful (0)

    More Products You Might Like

    Customer Reviews (1) Write a Review

    Overall Rating 5.0

    out of 5 stars

    Installation Time:Shop Install

    Installation Cost:$250-$500

    • Performance Gain 5 5
    • Fit 5 5

    • 5/5

      Installation Time: Shop Install

      Installation Cost: $250-$500

      October 22, 2015

      Worth every penny

      The process of getting the parts and advice needed to upgrade my gear ratios was priceless. I have total felt the difference in the gears. I am extremely happy with my mod. American Muscle customer for life!


      Year: 2015 Submodel: Ecoboost California

      Helpful (1)

    Related Mustang Categories