I am not an expert here by anymeans and I am sure that others may tell you ALOT better than I can. I would pull out the stereo and look in the back to check if the rear wire are plugged in. If not while you are back there you could hook some up. (I know sounds easier than it might be) Run the wire under the carpet or how ever you want to the rear where you hook up the rear speakers. I installed a new stereo in my 95. (much better with CD now.) I hope this helps. Like I said someone might tell you better or in more detail. Any questions let me know?
ralleyclimber