Differential

There are two different factory Differentials, R180 and R200.

R180 is smaller, and has a collar on the side where the stub shafts insert to the housing, the R200 does not.

Ring example

 

For size comparison

Above: Soft mounts (later R200)

Below: Hard Mounts (early R200)

R180 differential and it's subframe, and the axels are not cross compatible with the R200. If you're going from the R180 to the R200, you will need to acquire a new subframe and axels. The subframe's for both the S14 and S15 will work, and will not require extra modification for fitment of components such as arms from your factory R180 subframe. Drive shaft will work between the two, and they are the same length.

R180 diff housings on S13/R32 uses a 4 bolt Mount on the differential cover, and S14/after uses a 2 bolt mount So if just doing a swap, R180 for R180, change out the differential cover, and you'll be good to go.