The 'Auto spoiler' was an option for all R32s except the GT-R.
As has been posted 11tybillion times before, the only things that actually differentiate a Type M from the other R32s are the 4-pot front brakes/2-pot rear brakes, and the Viscous LSD. Digital climate control air con was standard too, but other GTS-ts (not Type M) could be optioned with it. I would add the GT-R lookalike 16inch wheels too, but so many cars have them swapped over or exchanged you can't really rely on that to tell you the difference anymore.
Optional equipment:
auto spoiler
rear wing
aero front bumper/side slirts/rear pods
CD player
metalic paint
Don't worry, far fewer GTS-ts (without 4-pot brakes etc) were sold than proper Type Ms. I've only ever seen one GTS-t here and in Japan, but seen countless Type Ms. The Type M is the one you want anyway...