I know for a fact that plain jane ZX3's did indeed have side impact sensors since the beginning. My original focus, a 2000 zx3 stripper edition had side impact airbags; I remember the little suede patch on the fabric seat cover.. As to the location of the sensors, I would presume that they are probably somewhere on the crash beam inside the door or in the way back of the front fender, near the door opening.
Current love affair: 2004 SVTF #953 (Josephina - pronounced hoe-se-fin-a)
RIP: 2002 SVTF #2358, Sent to graveyard on June 11, 2013. I will always remember the good times we had!!
This car made my hair go gray, and did not care.