28 or 31 ?

[2002edgeplussupercab]

How can I figure out if my differential has a 28 spline or a 31 spline input ?

 

[adsm08]

Axle tube sizes are the easy indicator. If they are straight the whole way it should be 31 spline, if they neck down a bit at the end they are 28.

If you don't have an FX4 you probably don't have a 31 spline, unless a PO swapped it in.

 

[2002edgeplussupercab]

Thanks. Mine is 7.5" open 3.73 in a 2002 4dr Scab Edge with 3.0 and 5 sp auto so it should be 28 spline ? Correct ?

 

[adsm08]

Oh yes, all the 7.5s were 28 spline.

 

[2002edgeplussupercab]

Thank You ! That helps emmensely !

 

[adsm08]

Also, you phrased the question wrong.

The input to the axle is the pinion gear, which doesn't have different spline counts on the 8.8. The axle shafts are what changed, and those are the output.

 

[2002edgeplussupercab]

Thanks for the education !