i've got an S5 with an S5 NA open diff in the back, i've got a spare S4 GXL diff and the clutch pack is still nice and tight. i'm looking to put it into my car, but i want to know if the S5 na axels will bolt up to the S4 na diff. i've searched and can't find SFA. thanks.

 

All N/A interchangeable, no problem.

 

Ya,Doc..the s4 and s5 diffs can use the same n/a half shafts.
the only big difference really on the drivetrain is the Tranny mount.which needs to be series specific.
The 4 lug and 5 lug can be run with the same N/a Axles,as they have the same spline input for the half shafts.
it is the same too on the Hub side on the TII axles,but not on the DIff side,thet is where they change,That is why you can't run N/A axles on a Tii Diff.the flange parts are different.

 

thanks guys. yet again, great info.

 

since you are going to change the diff, make sure to change the rear diff mounts and front mounts, and maybe install a pinion snubber also.