I have an 88 vert with the headrest speakers. The previous owner had an aftermarket stereo installed but they didn't hook up the headrest speakers. I have had the stereo out of the dash but did not see any extra wires or plug. There appears to be a factory amp or control box behind the driver's seat under the spare tire cover that I assume operates the headrest speakers. I have found a black cable with a round plug on it under the dash next to the steering column. Sort of looks like what I think they call an "S" cable that hooks up a TV. Does anybody know if this is the wiring that I am looking for?? I don't have much experience with stereos. In my time the engines in the cars thumped not the stereos!!

 

Most people with aftermarket stereos just hook up the back channel of the indash unit directly to the headrest speakers, bypassing all the OEM electronics. This is the easiest way to reactivate the headrest speakers in your case.

It is pretty hard to tell what previous owner did on an aftermaket stereo install. Some people are really sloppy and have a very poor understanding of electronics and wiring. If you are unconfortable with this subject, go to a good local installer (not the boys at major chain stores) and have them work it out for you.

Good luck.