28 spline to 31 spline axle conversion questions

Redlines · Nov 15, 2019

Hi can anyone tell me what else besides this kit I need to convert my 02 GT to 31 spline axles. I also have a Ford Racing 3.55 ring/pinion to go with it.

I also have access to a GT 500 complete rear end I could get if I can convert it with that, only had 20k miles on it when pulled

https://lmr.com/item/LRS-4204D-K/99-04-Mustang-88-31-Spline-Rear-Axle-Conversion-Kit

D3VST8R96GT · Nov 17, 2019

The only thing you can use from the GT500 will be the diff cover and center section. It is a 31spline center section though.

Depending on your mileage you might want to do the bearing kit. https://lmr.com/item/M4210C3/mustang-ford-performance-ring-pinion-install-kit-m-4210-c3
Otherwise the regular gear install will be enough is everything is in good shape.

Redlines · Nov 17, 2019

So I need the 31 spline center section to do the conversion or does the conversion kit include that.
Thanks

ttocs · Nov 17, 2019

you will need a 31 spline diff, that kit shown above does include it. You might want to consider upgrading the diff cover while you have it off. A new one will add strength and allow you to drain it with out taking the cover off. Not sure if you are planning on doing this yourself? I did because I had a buddy that said he had done a bunch so I thought with his help and the vids I saw it would be ok. I realized pretty quick that he didn't have the experience he said he did and ended up paying for it to be done right.

Redlines · Nov 18, 2019

Thanks for the help. It's looking like it's going to be too expensive.
I just wanted my ring and pinion changed out to 3.73 and my True-Track rebuilt.
The shop said it would cost more to rebuild the true trac then it would be to just drop in a locker. They must have assumed I had 31-spline Axel's because a 28 spline locker is almost double a 31 spline.
I'm getting quoted labor prices of 500-900 just to change out the ring and pinion and rebuild the truetrac and that's with me supplying all the parts.
Anyone got a good recommendation for a rear end shop in the Bay area/Northern California