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Ford Performance IRS Ring Gear and Pinion Kit - 3.55 Gears (15-20 All)

Market Price $208.17 You Save 47% ($97.18)
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  • Item 384402

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    Features & Details

    • Ford Racing Quality
    • Strong Forged Construction
    • 3.55 Gear Ratio
    • 8.8" Ring Gear Diameter
    • For Street or Track Use
    • Fits 2015-2020 Mustangs Equipped with IRS
    Upgrade OEM Gears. Are you looking to upgrade to a stronger set of rear gears? Then look no further than installing a set of genuine Ford Racing Gears in your 2015-2020 S550 Pony. Ford Racing Ring and Pinion Gears are perfect for street, road, and race applications.

    Superior Quality. Manufactured in the USA, these Ford Racing Mustang ring and pinion gears feature a super strong forged construction, CNC cut & lapped gear teeth, and are completed in a black oxide finish to resist corrosion.

    Recommended Upgrade. Changing the rear axle gear ratio will throw off the calibration of your Mustangs speedometer, but a Mustang Handheld Tuner is a quick and easy way to fix this issue.

    Application. This 3.55:1 Ratio Ford Racing Ring and Pinion Gear set will fit all 2015-2020 Mustangs equipped with an 8.8" Independent Rear Suspension (IRS), including V6, EcoBoost and GT models. A master bearing kit is recommended by most installers, especially on high mileage vehicles.

    Application Note. These Ford Racing 3.55 gears are

    not compatible with a 3.15 ratio differential - use differential M-4204-MT or M-4204-M.

    Technical Note. Installation costs will vary, but a good rule of thumb is between $250 and $300. Be sure to work with a reliable shop that you trust for installations.

    Fitment: 2015 2016 2017 2018 2019 2020 Details

    MPN# M-4209-88355A

    CA Residents: WARNING: Cancer and Reproductive Harm -

    What's in the Box
    • (1) Ring gear
    • (1) Pinion gear
    Installation Info
    Tech Specs
    Will it fit my Mustang?
    • Bullitt - 19, 20
    • EcoBoost - 15, 16, 17, 18, 19, 20
    • GT - 15, 16, 17, 18, 19, 20
    • GT350 - 15, 16, 17, 18, 19, 20
    • GT350R - 15, 16, 17, 18, 19, 20
    • GT500 - 20
    • V6 - 15, 16, 17

    These 3.55 gears are not compatible with a 3.15 ratio differential - use differential M-4204-MT or M-4204-M.

      Customer Photos

        Questions & Answers (19)

        5 Top Rated Questions

        Hi i got a 16 gt supercharged manual i belive i have the 3.31 gear ratio i was thinking on changing these for a 3.73 or what would you recommend for my ride thanks

        • Selecting gears comes down to a number of factors, including the primary type of driving done, tire size, and the amount of power you are making. On a supercharged 2016 Mustang, typically the best gearing will come from either a 3.31, a 3.55, or a 3.73, depending on several factors. Please give us a call at 1-844-872-1535 to speak to one of our experts about which gears would be best for your particular setup.

        Helpful (3)

        "These 3.55 gears are not compatible with a 3.15 ratio differential - use differential M-4204-MT or M-4204-M." How do I know if my V6 has a 3.15?

        • Hello! The two easiest ways to find out which gears you have in your car is to; First, have your dealership check your VIN, or Second look on your differential as there is a stamp that will tell you.

        Helpful (1)

        My 2016 eco boost has 5500 miles on it. Do I need to change the diff bearings with this low amount of miles on them?

        • Assuming the vehicle does not have excessive wear and tear, there is no need to change the diff. bearings with that amount of miles.

        Helpful (0)

        Hi, I see a lot of questions about going up from 3.15, 3.31 to 3.55, but I couldn't find any about going down. I have a PP GT w/ 3.73s and the Torsen Diff - I'm going forced induction and want to move down to 3.55 but want to keep the Torsen and was hoping to just switch out the gears; it looks like this would work, but I thought I'd check. Thank you.

        • 3.55 gears can be used with the Torsen differential.

        Helpful (0)

        I have a 2015 v6 automatic trans mustang, I also have a 91 octane tune, borla cat back exhaust and a roush cold air intake. 3:55 were an option for my car when new so would I be safe in installing 3:55 in my mustang with the stock drive shaft. Is the 2015 drive shaft stronger than 2014 and ealier shafts?

        • Yes, you would be able to upgrade to 3:55s without any issues.

        Helpful (0)
        Post Your Question
        10 More Questions
        Is this identical to the factory equipped gears. 1 answer
        Hi, I have a 2015 mustang gt automatic with the 3.15 gears. If I buy this set and this (M-4204-M) will I need anything else besides maybe a new seal kit to install them on my car. Thanks 1 answer
        Would this set up fit on my 2015 ecoboost mustang? 1 answer
        I have a 2015 v6 automatic trans, my current gearing is 3:15 standard gears, will these 3:55 work on my car? 1 answer
        hello, its can go on a mustang 2015 basic v6 ...?????? 1 answer
        Will this fit a 2016 mustang v6 with the stock 3.15 ratio? 1 answer
        How can I tell what rear end Ratio , I have in my V6 Mustang 2015 ????It doesn't say on the Invoice???? 1 answer
        Are the 3:55 or 3:73 compatible with the 2016 v6 in manual? Also, will other performance parts be necessary to hand the those gear ratio's? 1 answer
        I have a 2016 v6 mustang and I want to upgrade from my 3.15 gears what will I need 1 answer
        Will these gears work on my ecoboost mustang auto? I have the 3.31 gears now stock 1 answer

          Customer Reviews (4) Write a Review

          Overall Rating 5

          out of 5 stars

          Installation Time:Full Day

          Installation Cost:$250-$500

          • Performance Gain 5 5
          • Fit 5 5

          • 5/5

            Installation Time: Afternoon

            November 23, 2018

            Gear change

            I needed a little higher rear end ratio for my ride. The 3.55's did the trick


            Year: 2015 Submodel: GT

            Helpful (8)

          • 5/5

            October 11, 2017

            What can I say,it's made by Ford Performance

            I use Ford Performance parts whenever possible. I know that it will fit and perform as advertised.


            Year: 2017 Submodel: GT

            Helpful (14)

          • 5/5

            Installation Time: Shop Install

            Installation Cost: $250-$500

            June 14, 2017

            Its Ford Performance

            I ended up not installing as I decided to go FI. The quality and appearance are top notch. I gave them to a fellow S550 driver who went from the 3.31 to the 3.55. He is staying NA so it works out. I drove his car after the swap and it definitely pulls much harder. First gear is not useless though like with the 3.73s.


            Year: 2015 Submodel: GT

            Helpful (17)

          • 5/5

            Installation Time: Full Day

            December 28, 2015

            Great upgrade from the 3.31

            This is the OEM Ford Racing 3.31 gears. Exceptional build quality/fit/finish. The price is unbeatable from AM as well - you can't go wrong!


            Year: 2015 Submodel: GT Mohnton, PA

            Helpful (15)

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