i noticed something while looking at jdm motors at work.
basically the last 10 jdm itr motors have serial number that starts with 2,
ex.itr B18C
273819

and the last few jdm gsr i saw al had numbers that start with 1.
ex. gsr B18C
132754

i hope this help others identify jdm motors, whether its a itr or gsr.
also if anyone out there can prove me wrong, pls do so as this is only based on the motors i have seen and i might be wrong.