My GTR is just a normal GTR and my model is KBNR32RXFS7, the 7 on the end means it's a normal GTR, if it was an 8 it means it's a V-Spec II, if the number is absent, it's a V-Spec I.
Also the KBNR32RBFS, B means it has 17" V-Spec wheels.
http://www.users.on.net/~goofyhsk/info/chassis_plate.html