An S5 viscous fluid type differential until will bolt to the ring gear in an S4 case correct?

Thanks,
- Cooper -

 

Yes, the LSD units are interchangeable. If this LSD unit is from a NA 89-90 (the "GTUs" model), than you'll need to use the output shafts for that specific unit since the left and right are of different lengths.

Hot_Dog
90 RX7 GXL
02 RSX-S