Stereo & Electronics - 1993 Shocker.....

So I go to put in a 10" Eclipse sub in an MTX box that I got from a buddy. I find out I've got a Bose speaker in the rear of the car, no biggie. Pull it out, wire the amp, yadda, yadda, yadda. Got to check the system and the subs not putting anything out. Well very minimal if anything. Now it has me thinking either the sub or the amp are bad. Whatever they were free. So my wife comes out and says "What's up?" I tell her the whole story she proceeds to look in the car while the stereo is on and goes "There's nothing from the back seat." Now I'm curious what the heck she's hearing. Sure enough no sound from the rear speakers in the panel right next to the back seats.. Both sides, now I'm wondering. Pop the grills off and see some sound deadener. Push through the sound deadener and not a thing. Turns out I have no speakers there! There are a whopping 3 speakers in my car! No this thing is 99.5% stock, so nothing really surprises me, but really?!?!? Is this normal for a 1993 Z28 A4? The thing doesn't have anything special that I know of, butthis has me stumped as I really don't want to go spend money and time re-wiring the two rear speakers.....

Sorry for the long post, I know it's mostly jibberish

That's normal - the Bose system was available in a 3-speaker and a 5-speaker configuration. The 3-speaker configuration had door speakers and a sub in the back, the 5-speaker configuration added the sail panel speakers.

The Bose system is difficult to upgrade because it used a special head unit that output low-level, high impedance (32-ohm) signal to individual amps attached to each of the low impedance (1-ohm) speakers.

I already swapped out the head-unit for a Jensen in dash DVD player (more for the kids than myself), so that I'm not worried about, I was just a little shocked to see that two of the speakers that I was used to were missing. Kinda shocked the hell outta me.