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8.8 in. 31 Spline Axle and 3.73 Gear Upgrade Kit - 4 Lug (86-93 5.0L)

2 Reviews
Our Price

$1,019.99

(kit)
  • Item #99907
  • Market Price $1,152.59
  • You Save 12% ($132.60)
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Features
  • Put the power to the pavement
  • Ford Racing Traction - LOK limited slip differential with carbon discs
  • Ford Racing 3.73 gears
  • Ford Racing differential cover
  • Ford Racing 8.8in rear axle bearings and seals
  • Moser 31 spline 4-lug axles
  • Rear end installation and bearing kit
  • (2) bottles of Royal Purple Max Gear 85w140 Gear Oil
  • Fits 1986-1993 5.0L V8 Mustangs with 8.8" rear end
Description
Performance Upgrade. Now you can upgrade the rear end of your 5.0L Fox Body Mustang to handle more power. This kit will replace your wimpy stock factory 28 spline rear with a heavy duty 31 spline setup that includes a Limited Slip "Posi" Differential, 31 spline 4-lug axles, steeper 3.73 gears and a aluminum differential cover. Best of all you can still use your existing 4-lug wheels.

Kit Includes. This 4-Lug 8.8in 31 Spline Axle and 3.73 Gear Upgrade Kit includes Ford Racing Traction LOK Limited Slip Differential, 3.73 Gears, Aluminum Differential Cover, Rear Axle Bearing & Seal Kit, Moser 8.8 31 Spline 4 Lug Axels, Motive Rear End Installation and Bearing Kit and (2) bottles of Royal Purple Max Gear 85w140 Gear Oil.

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

Application. This 8.8in 31 Spline Axle and 3.73 Gear Upgrade Kit will fit all 1986 to 1993 5.0L V8 Mustangs including the LX 5.0, GT and SVT Cobra models equipped with 4 lug wheels.

Mustang Fitment: 1986 1987 1988 1989 1990 1991 1992 1993 Details

What's in the Box
  • (1) Ring gear
  • (1) Pinion gear
  • (1) Limited Slip Differential
  • (2) 31 Spine Axles
  • (2) Outer Axle Shaft Bearings
  • (2) Seals
  • (2) one quart bottles of Max Gear 85w140 Gear Oil
  • (1) Axle Girdle Assembly
  • (1) Axle Girdle Gasket
  • (10) Washers
  • (10) Bolts
  • Front & Rear Pinion Bearing
  • Pinion Seal
  • Carrier Bearings
  • Carrier Shims
  • Differential Bearings
  • Crush Sleeve
  • Pinion Nut
  • Cover Gasket
  • Ring Gear Bolts
  • Brush
  • Gear Marking Compound
  • Loctite
Installation Info
Tech Specs

Approximate RPM for 1986-1993 GT


Manual
Gear @25 MPH @35 MPH @45 MPH @55 MPH @65 MPH @75 MPH
1 3876 5427 6977      
2 2289 3205 4120 5036 5951 6867
3 1100% 2142 2754 3366 3978 4590
4 1150 1610 2070 2531 2991 3451
5 771 1079 1387 1695 2004 2312


Automatic
Gear @25 MPH @35 MPH @45 MPH @55 MPH @65 MPH @75 MPH
1 2761 3865 4969 6073    
2 1687 2362 3037 3712 4386 5061
3 1150 1610 2070 2531 2991 3451
4 767 1074 1380 1687 1994 2301
Will it fit my Mustang?
  • Foxbody - 86, 87, 88, 89, 90, 91, 92, 93

Most Helpful Reviews Read All Reviews

Overall Rating 5/5 Write a Review
5/5
Real Nice Upgrade

Quality parts, no installment issues. A huge upgrade over stock.

Helpful (1) (0)

5/5
great product

i was very happy with the product. my boyfriend was very happy with it. it was given to him as a gift. will be buying again in the near future. Thank You

Helpful (1) (0)

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5.0

out of 5 stars

2 Customers Recommend this Product

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  • 5/5 Yes, I recommend this product

    October 11, 2014

    Real Nice Upgrade

    Quality parts, no installment issues. A huge upgrade over stock.

    JayV

    Year: 1990 Model: GT 'Stangs I have owned: 1 MA

    Helpful (1) (0)

  • 5/5 Yes, I recommend this product

    January 25, 2014

    great product

    i was very happy with the product. my boyfriend was very happy with it. it was given to him as a gift. will be buying again in the near future. Thank You

    jess209

    Year: 1991 Model: GT Driving Style: Street / Strip 'Stangs I have owned: 2

    Helpful (1) (0)

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