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Swap a rear axle from a '99 into my '98

Discussion in '1994-2004 V6 Mustang Tech' started by BryanSmith, Sep 15, 2017.

  1. BryanSmith

    BryanSmith Member

    Sep 1, 2017
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    Fort Wayne, Indiana
    My '98's rear axle is not long for this world...whines and howls loudly.
    I suspect a pinon bearing, but I am not gonna get to deep in investigating who, what, where and why.
    At my local Pick a Part yard, I have been harvesting parts from a really nice '99 V6 Mustang.
    My plan is to go drop that '99's rear 7.5" axle in the mud and haul it home.

    Now, where I do to investigate is what issues will I run into with this swap.
    I will blindly assume that that '99 axle will bolt into my '98 car.
    My list of things to check on for issues are:
    • shocks
    • brake hard line
    • E brake line
    • ABS wiring
    • u-joint cap size
    Doing some searching here, I discovered that my '98 axle has a 2:73 ratio and the '99 has a 3:27.
    Nice!! That's gonna make banging that 5 speed just that much more fun!

    How will I recalibrate the speedo from 2:73 rear end to the 3:27?

    What are the opinions, comments, suggestions and flames of the community of this 'Roadkill' plan of mine?
  2. six gun

    six gun Active Member

    Jun 26, 2014
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    South Dakota
    First, I believe 99-04 rear ends are a shade wide than 94-98. But, it should bolt up the same. I believe the brakes back there may be different as well, not sure if the mounting brackets between the two are the same or not.

    I can't speak for the speedo calibration - I do know 99+ have electronic speedo output on the trans, but not sure when 94-98 made the change from mechanical to electronic. I wanna say its still mechanical up to 98. If that's the case, there are different mechanical gear pick-ups that exist to calibrate speedometer for gear changes back on the transmission. Otherwise if you find out its electronic, might be handy to get a handheld tuner for your car and calibrate it via a tune.
  3. douglass

    douglass Active Member

    Aug 8, 2013
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    Bay Area, California
    You should need a red speedo gear to re calibrate the speed with the 3.27 gears. If you can find a 96-98 GT you can pull the red gear from the speed sensor. The drive shaft should bolt up to the existing flange. The control arm bushing should bolt up, not sure on the ebrake cable. Per Rockauto the parking brake cable is 99-04, so you might want to grab them. Looks like the brake caliper/bracket is the same from 94-04. If you can find a 96-98 Mustang GT, you could get the 8.8 rear end which has the 3.27 gears, and a posi-trac diff. The 8.8 will also bolt right up to everything, and is stronger.