that one looks like a S1.5 - S1 front with S2 wing and the clear skyline boot garnish
the higher wing came on the S2 models, and on the S1.5 models
S1 is series 1 - info can be found here
S1.5 is series 1.5 - info can be found here , this is basically a S1 with the S2 wing and engine.
S2 is series 2 - info can be found here
more info on model differences can be found here
it is mainly cosmetic changes and standard options, there is other things like the coil igniter module as noted above
you can post the VIN number (number on firewall) in these threads and someone with the Nissan FAST program will check it out for you
http://www.skylinesaustralia.com/forums/in...howtopic=133729
http://www.skylinesaustralia.com/forums/in...howtopic=128496