Q naturally aspirated and k turbo slight difference in aero option packages. In the u.s they were all 240sx,s. 88 to 94, s13 . 95 to 98 s14. We never got the s15. Sileighty is when you swap the pop up lights on an 180sx s13 hatch and replace it with the Silvia grill and head lights. Sil/eighty. Hope this helps.