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Ford Performance IRS Differential Cover; 8.8 Inch (99-04 Cobra)

Item 50383
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      Product Information

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


      • Superior Strength
      • Light Weight Aluminum Construction
      • Includes Fill and Drain Plugs
      • Direct Fit Replacement
      • Fits 1999 to 2004 SVT Cobras w/ IRS


      Lighter and Stronger. When upgrading the rear gears in your SVT Cobra it's a good idea to replace that wimpy stock Girdle Support System (a.k.a. differential cover) with a super strong, light weight Aluminum Differential Cover for additional safety and peace of mind.

      Ford Racing Quaility. Add performance parts to your Pony made by the people who know it best. This Ford Racing 8.8" Rear End Differential Cover is cast from lightweight aluminum for strength and features convenient fill and drain plugs. The load bolts provide additional support for the differential bearing caps to increase ring and pinion gear life.

      Recommended Upgrade. When changing your differential cover it is recommended to upgrade to fresh Royal Purple Synthetic Gear Oil. You will need 3 quarts of Gear Oil.

      Application. This Ford Racing IRS Rear End Differential Girdle Cover is designed to fit the 1999 to 2004 SVT Cobras equipped with the 8.8" Independent Rear Suspension (IRS) rear end. not for use on non-IRS Mustangs.

      Fitment: 1999 2001 2003 2004 Details

      MPN# M-4033-G3

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (29)

      Write a Review

      Ratings Summary

      4.8 out of 5 overall rating from 29 customers

      Installation Time: Full Day

      Installation Cost: $250-$500

      • August 14, 2019

        5 1999 Cobra - RobertC

        Diff cover

        Look like a great piece have not installed it yet. I am still breaking in my 4-10 gears in my 1999 mustang cobra.

        Helpful (0)
      • May 23, 2019

        5 2003 Cobra - Curt Installation Time: Afternoon

        Ford Performance IRS Diff Cover

        The differential cover is well made and much stronger than the OEM cover. It fit well and also had differential cap support bolts. I believe this will stop future differential cover leaks because I think the standard cover flexes under hard loads causing the leaks.

        Helpful (0)
      • May 21, 2019

        5 2003 Cobra - JeremyM Installation Time: Full Day

        Every Cobra IRS must have!

        Perfect solution to the weak cover. This and Delrin bushings are a must in an IRS. Wheel hop broke mine, mostly driver error on my part. Now I have some durability. I installed an diff cooler with the cover. This cover makes installing a diff cooler easier due to having accommodations for fittings.

        Helpful (0)
      • April 06, 2019

        5 2003 Cobra - stvenkng Installation Time: Afternoon

        Purpose and looks

        Fits, works, looks better and is stronger than stock, accommodates external cooler supports carrier bearings

        Helpful (0)
      • March 24, 2019

        5 2003 Cobra - stvenkng Installation Time: Afternoon

        Purpose and looks

        Fairly easy install, I was changing the gear to a Motive 3:90 so thought this would help strengthen the housing. Heavy built, oil cooler tube, fill and drain plugs, access for temp gauge. Worth the money, but might be a two man (or woman or X?,} job but you can knock it out in a couple of hours, three quarts of gear oil is a plus, runs cooler feels tighter.

        Helpful (0)
      • February 14, 2019

        5 2003 Cobra - CurtS Installation Time: Afternoon

        Ford Performance Cobra Rear Diff. Cover IRS Cobra

        I haven't installed it yet but it is very well made and much stronger than the factory cover. It also has plugs for a oil cooler as well.

        Helpful (1)
      • November 25, 2018

        5 2004 Cobra - Francisco Installation Time: Shop Install Installation Cost: $250-$500

        Ford Performance IRS Diff Cover

        I got this as a replacement due to my stock one leaking. My cobra has 700hp to the wheels, its been a year with the new cover on and it's withheld many hard launches. Definitely would recommend to anyone.

        Helpful (3)
      • August 31, 2018

        5 2004 Cobra - Tom Installation Time: Less than 1 Hour

        Super Strong IRS Diff Girdle

        Much thicker and obviously stronger than the original IRS cover. The original cover probably was good enough to contain the differential oil, but not the internal forces generated by a high HP engine. This will be installed on a FFR 535 HP Cobra Replica. Very easy to install since the IRS Differential was not yet installed on the FFR frame. No Mustang, but had to put a year in order to post the review!

        Helpful (5)
      • June 03, 2018

        5 2003 Cobra - RichardJ Installation Time: Full Day

        Nice piece great quality

        Really helps stiffen up your rear diff. A must have for IRS Cobras. Great craftsmanship. Even comes with all the hardware

        Helpful (6)
      • March 22, 2018

        5 2003 Cobra - JonF Installation Time: Shop Install Installation Cost: $100-$250

        Ford performance diff cover

        This is a very high quality cover , much thicker then stock one and much better looking. This cover should be a much stronger piece. I would recommend this product to all who are interested.

        Helpful (6)

      Questions & Answers (6 answers)

      5 Top Rated Questions

      Will this work with the Steeda IRS differential brace? I know that the LPW will not work with the brace.

      • No, but if you use this cover you no longer need a diff brace.

      Helpful (1)

      Tapped hole for mech temp sensor? Are one of those holes a tapped hole for a mechanical temp sender? Jim Morrissey/ aka. Jimmysidecarr

      • No, the top hole is for a diff cooling system, the middle one is the fill hole and the bottom is the drain hole. On the inside of the cover they have a place marked on it where you can tap and drill your own temp sensor hole

      Helpful (1) Show 2 more answers

      Can install this with diff still in car?

      • This can be installed without removing the diff.

      Helpful (0)

      How much gear oil is meant to be used with this cover? Some people report 2.5 quarts is too much. The original cover calls for 1.5-2 quarts.

      • The Ford Performance IRS Differential Cover requires 3 quarts of gear oil.

      Helpful (0)

      Is this cover compatible with the FTBR 1401 delrin lowering mount?

      • The Ford Performance IRS Differential Cover is compatible with the FTBR 1401 Full Tilt Boogie Delrin Isolated IRS Differential Lowering Mount.

      Helpful (0)
      Post Your Question
      1 More Question
      What gasket was used for this cover? 1 answer

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Girdle cover
      • (10) Washers
      • (10) Bolts

      Tech Specs

      Will It Fit My Mustang

      • Cobra - 99, 01, 03, 04

      Fits 1999-2004 IRS equipped Cobras Only

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