keyless entry setup help

I checked my mustang for the the large black box on the "LH rear QTR pannel" I didnt see a large box there. I only saw a gray plug with two pongs* like a electric socket. My car is a 97 gt and im wondering do all cars come from the factory ready to setup with a remote control. If i was to buy a remote could i setup or am i missing something?

I didnt see on the wall nearest to the fender so maybe its there. Im not sure how to get the thing loose to check. Is there anyway to check if your car is FOB ready?

thanks

edit: FYI: I know how to program it, but is there suppose to be anything infront of the gray wire.

I just tried the on off 8 times thing and nothing happened ;[

Also if my doors are locked and i lift the handle from outside no lights come on.

anyone?