Win $5,000 For Your Mustang! Enter Now!
Talk to a Mustang Expert
1-888-332-7930
Mon - Sun, 8:30 AM EST - 11:00 PM EST

Free Shipping On Orders Over $49. Details

Yukon Gear 8.8 in. Duragrip Posi Rear Differential w/ 31 Spline 5 Lug Axles (99-04 GT, Mach 1)

Market Price $657.99 You Save 9% ($59.82)
Our Price

$598.17 (kit)

FREE Shipping
  • Item 393820
  • MPN# 393820

In Stock Ships same business day. Choose options to add to cart

Features, Video & Details

  • Put the Power to the Pavement
  • 8.8" Limited Slip Differential
  • Heavy Duty Nodular Case
  • Forged 4320 Internals
  • Yukon 31 Spline 5 Lug Axles Included
  • Fits 1999-2004 GT, Bullitt and Mach 1 w/ an 8.8" Differential Housing

Review & Installation Video

Review & Install Video

Put the Power to the Pavement. Boost the performance and improve the road handling of your New Edge Mustang by upgrading to a Yukon DuraGrip Posi Rear Differential. This kit includes an 8.8in 31 Spline DuraGrip Posi Differential, a pair of 31 spline 5 Lug Axles and all the bearings and shims required for installation. This Yukon kit is ideal for those GT, Bullitt and Mach 1 owners who are looking to upgrade their stock differential and axles for better traction and more impressive burnouts.

Posi Rear Differential. The DuraGrip Posi Rear Differential features a case constructed from a heavy duty nodular iron and boast forged 4320 steel internals and composite clutches for dependable heavy duty performance and long life.

31 Spline 5 Lug Axles. Stronger than OEM, Yukon Gear manufactures their 31 spline 5 lug axles from high quality 1541H alloy steel for superior strength. They use a rolled spline process that produces an axle spline that is up to 30% stronger than standard cut splines.

Durable Alloys. The parts in this Yukon Gear and Axle kit are built from high quality, heat-treated metal alloys for long-term durability. Top quality ensures extended use before needing to replace the parts. This complete axle kit includes everything you need for optimal road handling.

Application. This Yukon Gear 8.8 in. DuraGrip Posi Rear Differential Upgrade Kit with 31 Spline 5 Lug Axles is designed for 1999 to 2004 GT, Bullitt and Mach 1 Mustangs equipped with a 8.8" rear differential housing.

Technical Note. 1986-2004 V8 Mustangs came factory equipped with 28 spline axles, except for 2003-2004 SVT Cobras which were 31 spline. You will need to reuse your factory 8.8” gear set, or upgrade to a set of our 8.8" rear gears required for this Limited Slip Differential. No aftermarket gears are included. For normal driving conditions we recommend you use 75W 90 rear gear oil. This will give you the same oil weight as factory. For colder temps or race use try 75w 140.

Fitment: 1999 2000 2001 2002 2003 2004 Details

What's in the Box
  • (1) 8.8" Limited Slip Differential
  • (2) 31 Spline 5 Lug Axles
  • Carrier Bearings
  • Carrier Shims
  • Axle Bearings
  • Seals
  • Studs
Installation Info
Will it fit my Mustang?
  • GT - 99, 00, 01, 02, 03, 04
  • Bullitt - 01
  • Mach 1 - 03, 04

People Who Bought This Item Also Bought

Most Helpful Reviews

5/5
Great buy

For the price you can't beat it. I had some bad bearings so I decided to upgrade the rearend of my 04 GT. AM customer support was a little slack when I asked them did this kit came with all the bearings ...

Read More
Helpful (1)

5/5
Awesome product

Just had this installed in my 2003 Mach 1 and I can say this was a great investment! Definitely can tell a huge difference from the stock 28 spline

Helpful (1)

Overall Rating 5 out of 5 stars
Read All 4 Reviews

Customer Photos

You Might Also Like

4 Questions / 5 Answers

Ask a Question

Does this come with ALL bearings and seals required for installation? Or do I also need to buy a bearing and seal kit?

JeremiahC

  • The will come with the Yukon Gear 8.8 in. Duragrip Posi Rear Differential w/ 31 Spline 5 Lug Axles will come with the hardware to install the differential. You will need to purchase the additional ring and pinion install kit which will include shims to install your gears back into your rear.

    AMCoal

Helpful (0)

Stupid question but would this fit an automatic 2000 Mustang Gt?

EricE

  • Hello! The Yukon Gear 8.8 in. Duragrip Posi Rear Differential w/ 31 Spline 5 Lug Axles will fit on a automatic 2000 GT

    VincentV

Helpful (0)

Can this kit be used to convert a 99-04 V6 to a 8.8" rear end, assuming I acquire an 8.8" rear end housing? Is the driveshaft connection point the same or will that need to be swapped to one compatible with the 8.8" rear end? If driveshaft needs to be changed which one is going to be compatible with the T5 5-spd in my V6?

G

  • All this stuff fits in a 8.8 no problem.

    JeremyS

Helpful (0)

So what ratio of ring and pinion are with this differential or do we have to use our own? (2000 v6 Mustang with GT 8.8 in. conversion)

Stangwraith

  • You can use your old ring and pinion as long as it is an 8.8 rear end. I would suggest going to a 3.73 ratio. This setup is heavier than stock. You will feel a slight loss of power due to drivetrain weight. I love the 3.73... You can't go wrong with it.

    JeremyS

Show 1 more answer Helpful (0)

More Products You Might Like

Customer Reviews (4) Write a Review

Overall Rating 5.0

out of 5 stars

Installation Time:Full Day

Installation Cost:$500-$1000

  • Performance Gain 5 5
  • Fit 5 5



  • 5/5

    Installation Time: Shop Install

    Installation Cost: $500-$1000

    June 24, 2017

    Great buy

    For the price you can't beat it. I had some bad bearings so I decided to upgrade the rearend of my 04 GT. AM customer support was a little slack when I asked them did this kit came with all the bearings for the rearend which it doesn't. But besides that it's a great buy.

    Sidney

    Year: 2004 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    June 23, 2017

    Awesome product

    Just had this installed in my 2003 Mach 1 and I can say this was a great investment! Definitely can tell a huge difference from the stock 28 spline

    MikeT

    Year: 2003 Submodel: Mach 1

    Helpful (1)

  • 5/5

    Installation Time: Full Day

    April 14, 2017

    Much better than Ford LSD

    I installed this in my 99 5spd GT. My factory LSD was shot and so where my axle bearings. I went through slot trying to get rid of clutch chatter. My biggest mistake ever was changing fluid brands. Put only Royal Purple 75-90 and only Ford brand LSD fluid, I put 2 bottles of Ford posi fluid. Car always launches straight with equal wheel spin. I tried everything the Yukon techs told me for months. Nothing worked. I broke it in with R.P. and it was perfect. At 500 miles I swapped in Lucas synthetic.... Mistake! So was conventional oil. Clutch chatter to the point it sounded like gears were chewing themselves. Put R.P. back in and it and it is super quiet.. I recommend a larger diff cover to allow more oil capacity. This posi displaces almost 3/4 of gear oil. I went from 3.23 to 3.73 Ford GT 500 ring and pinion bearing install kit also. Rear end is bulletproof now. I changed oil and inspected everything 5 times. Still looks like new a 2k miles, 10k I have zero issues. This is my D.D. too, still get 20-25 mpg

    JeremyS

    Year: 1999 Submodel: GT

    Helpful (1)

  • 5/5

    December 23, 2016

    Yukon kit

    Its a great product. Very well built and heavy duty, also a good deal.

    04stang

    Year: 2004 Submodel: GT

    Helpful (1)

Related Mustang Categories