mustang gt rear end/differential rebuild cost vs doing it myself


Oct 28, 2020
Hello, the rear differential on my car seems to be bad. Mechanic said there is a 1/4" or 1/2" play (cant remember properly) when he moves the driveshaft and the best quote I had was $1600 for rebuild. I need to decide whether to have a shop do it or do it myself.

If I do it myself then I am thinking of getting a new carrier with spider gears installed here ($350):

or I can get a used one like this:

I will need a shop to press the races on with the bearings. A yukon bearing kit including shims is for about $85 on ebay.

A backlash gauge is about $90 and a ford racing 3.73 pinion/ring gear is about $170 on ebay. A used 3.27 set is about $115 on ebay.

A gasket is about $12.

I could try to rebuild the differential using all these parts without taking out the old one in case I can't do it or mess it up. If it goes well then I can just replace the rebuilt differential with the old one right? Am I thinking this too simplistically or am I being realistic? What am I missing? That is about $450-700 to do it myself plus whatever a shop will charge me to press the bearings/races if needed. I will mark everything else with a punch or paint so that I can put it in the same way it came out.

The thing I am concerned with is properly putting the c-clips back on as that is the only thing holding the axle shafts in. Is there a way to verify I have done it properly? Also what is the difference between 31 and 28 splines? What part is this referring to? Are they interchangeable? My car is a 2000 mustang gt with manual transmission, what will the stock/factory splines and gears be on this car? I think the stock are 3.27 gears from my other thread. Also I bet there is all the metal shavings going around, will they have damaged anything else like the housing? It might be better to keep everything stock for my use.

Thank you for your help.
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Apr 16, 2015
First off, what kind of play? Rotational or up and down movement at pinion? If rotational, was it play in the rear end or driveshaft (could be u-joints).

Removing and installing the c-clips is probably one of the easier aspects of the rear end build. Not hard putting them in.