2015-2023 Mustang Ford Performance 3.73 Rear End Gear & Install Kit by Ford Performance

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2015-2023 Mustang Ford Performance 3.73 Rear End Gear & Install Kit

Improve acceleration in your 2015-2023 Mustang with this Ford Performance 3.73 full rear end gear kit! Available at!

Item #LRS-4209FRI-K

Everyday Low Price: $424.99

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  • Improved Acceleration
  • Eliminates Guesswork
  • Complete Kit


  • 3.73 Ratio
  • Heavy Duty Construction
  • OEM Replacement Parts

 What's in the Box

  • (1) 3.73 Pinion Gear
  • (1) 3.73 Ring Gear
  • (2) Crush Sleeve
  • (2) Pinion Nut
  • (1) Pinion Bearings
  • (1) Pinion & Carrier Shims Set
  • (1) Pinion Seal
  • (1) Ring Gear Bolts Set
  • (1) Carrier Bearings Set
  • (1) Gear Marking Compound
  • (1) Bottle of Ford Racing Friction Modifier
  • (2) Bottles of Royal Purple 75W140 gear oil

2015-2023 Ford Performance 3.73 Gear Kit
This Ford Performance 3.73 rear end gear kit is perfect for getting faster acceleration in your 2015-2023 Mustang! This kit fits S550 IRS rear ends and includes everything you need to swap out or upgrade your stock gears. This kit includes Ford Performance 3.73 rear end gears, bearings, shims, gaskets, seals, gear oil, friction modifier and all of the hardware needed to get them installed. These performance gears do not add horsepower, but will definitely get your Mustang getting off the line faster!

Ford Racing Friction Modifier
This friction modifier is a specially formulated additive to provide smooth operation of clutch-type limited-slip differentials. 1 bottle of friction modifier is required when changing the gear oil in rear ends equipped with Ford traction-lock units.

Installation Note
  • Although the Royal Purple gear oil has friction modifier mixed in, it is still recommended that you use the bottle of Ford Racing friction modifier to supply your Super 8.8" IRS rear end with the proper amount of modifier.
  • LMR recommends the 75W140 viscosity for all 2015+ 8.8" differentials as it is appropriate for most climates, fuel economy, and performance.
  •  3.15 ratio differential is not compatible with 3.31, 3.55, 3.73, and 4.09 ratio gears. Use differential M-4204-M.

  • Fits 2015-2023 Mustang w/ Super 8.8" IRS Rear End

Ford Performance Racing Parts "Packs" and Component Parts Limited Warranty - Click Here
Ford Performance Racing Parts - NO WARRANTY - Click Here
Ford Performance Racing Parts Crate Engine Limited Warranty - Click Here

  • Ford Mustang - 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023

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About This Brand

Ford Performance
Ford Performance - Mustang Ford Racing Parts
Ford Performance Parts is the leader in performance parts and accessories for Mustang and Ford Lightning. is proud to offer Ford Racing Performance Parts for your project. Ford Racing is dedicated to manufacturing the highest quality products offered in the industry. Choose from suspension, exhaust, wheels, and other performance parts at Late Model Restoration. If you want the best for your Mustang or SVT Lightning, look no further than Ford Performance Parts!
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