I was looking at GTP (importfan.com) and noticed they had chassis reinforcments for the RPS13 and S13 only (Example Here), also like floor support bars, tension gauges and rear cross bars. I have a 1990 RHS13 and was wondering what the physical differences were between all of three and if these things would be interchangeable.

 

S13 = Silvia
RPS13 = 180sx

As far as chassis reinforcementts go they should work for any S13 no matter if you buy it for an S13 Silvia or 180sx.

 

S13=CA Sivlia
RS13= CA 180SX
PS13=SR Silvia
RPS13=SR 180SX
HS13=KA(E) 240 coupe
RHS13=KA(E) 240 hatch
MS13=KA(DE) 240 coupe
RMS13=KA(DE) 240 hatch

those are the basics.

 

Good Deal Thanks, So i guess they would all be interchangable