The Ford parts dept just tried to tell me that there were four. (2 fore and 2 aft of the cats) I disagree with him and tried to tell him that I was pretty sure that was only on OBDII cars, which would be '96 and up.
So, assuming I'm right and there are only two on a '90, in what year did they start putting four on?
So, assuming I'm right and there are only two on a '90, in what year did they start putting four on?