AFAIK there not eactly the same, but very similar.

I think 3 out of the 4 bolt up directly and the last one is out small, whinch can be modified to fit.

I think most of the s bodied are the same, as is the R bodies apart from the r34 gtt, which is different.

All this is what iv read, not experiecned, so not 100% sure. Iv a R34 GTR here that im looking for a bride base mounted passenger rail, so iv been researchin what rails will fit, id be happy with a s or r body seat rail if i could find one...