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USA Standard 3.90 Gears (99-04 GT)

AmericanMuscle no longer carries the USA Standard 3.90 Gears (99-04 GT). Please check out 1999-2004 Mustang Gears for an updated selection.
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$149.99

  • Item #21615G99
  • Market Price $169.99
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AmericanMuscle no longer carries the USA Standard 3.90 Gears (99-04 GT). Please check out 1999-2004 Mustang Gears for an updated selection.

Features
  • USA Standard Gear
  • Manufactured from 8620 gear steel
  • 3.90 gear ratio
  • 8.8" ring gear diameter
  • Fits 1999-2004 GT, Bullitt, Mach 1, and SVT Cobra Mustangs
Description
Wake Up Your Pony. Installing a set of steeper gears is a great way to get your Mustang into the power band quicker for improved low end torque and faster acceleration off the line. A set of USA Standard Gears will really wake up your Pony. Better Than OEM Quality. Using state-of-of-the-art equipment and manufacturing techniques USA Standard Ring & Pinion sets are made to higher than OEM standards from high grade 8620 gear steel and are backed by a one year warranty.

Recommended Upgrade. Changing the rear axle gear ratio will throw off the calibration of your Mustangs speedometer, but a Ford Racing Speedometer Recalibration Tool is an inexpensive way to fix this issue.

Application. This USA Standard Gear 3.90 Ring and Pinion Gear set will fit all 1999 to 2004 V8 Mustangs including the GT, Bullitt, Mach 1 and Cobra models. A master bearing kit is recommended by most installers, especially on high mileage vehicles, see drop down option above.

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.

Mustang Fitment: 1999 2000 2001 2002 2003 2004 Details

What's in the Box
  • (1) Ring gear
  • (1) Pinion gear
Installation Info
Tech Specs

Approximate RPM for 1999-2004 GT


Manual
Gear @25 MPH @35 MPH @45 MPH @55 MPH @65 MPH @75 MPH
1 4065 5691        
2 2405 3368 4330 5292 6254  
3 1588 2223 2858 3493 4128 4763
4 1203 1684 2165 2646 3127 3608
5 818 1145 1472 1799 2126 2453


Automatic
Gear @25 MPH @35 MPH @45 MPH @55 MPH @65 MPH @75 MPH
1 3416 4782 6148      
2 1864 2610 3355 4101 4847 5592
3 1203 1684 2165 2646 3127 3608
4 842 1179 1515 1852 2189 2526
Fitment
  • Bullitt - 01
  • Mach 1 - 03, 04
  • Cobra - 99, 01, 03, 04
  • GT - 99, 00, 01, 02, 03, 04

Customer Photos

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Q & A (1 Questions, 1 Answers) Ask a Question

gears and speedo I have a 2004 GT convertible, going to switch to 3:90 rear which will throw of the speedo, is this something that is fixed with an upgraded Bama Tune or do I have to get the ford product to adujst the speedo?

Bob04gtconvertible Year: 2004 Model: GT

Question Resolved
Good Question (0) (0)
  • The Bama custom tune can absolutely take care of the speedometer recalibration after upgrading your rear gears!

    Helpful (0) (0)

    LisaS Year: 1992 Model: GT

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