S Chassis Codes

'88-'90 S13 Silvia CA18DET
'90-'91 RS13 180SX CA18DET (R for fastback)
'91-'93 PS13 Silvia SR20DET (P for SR)
'91-'98 RPS13 180SX SR20DET (no distinction between the two different minor model change, last minor change was the inclusion of the double round lights and a more squarish front bumper.)
'91-'93 KPS13 Silvia (K for SuperHicas)
'91-'93 KRPS13 180SX
'89-'90 HS13 240SX KA24E (H for KA24E)
'89-'90 RHS13 240SX FB
'91-'94 MS13 240SX (dunno chassis code for convertables)
'91-'93 RMS13 240SX FB(M for KA24DE)
'91-'93 KRMS13 240SX FB w/ SuperHicas
'91-'93 KMS13 240SX w/ SuperHicas (Canadian market only).
'94-'98 S14 Silvia SR20DET
'94-'98 CS14 Silvia w/ SuperHicas
'95-'98 S14 240SX KA24DE (no specific S14 code for KA24DE

Excerpt from r20det.nismo.org"