Be prepared for a lot of work, The setup in your 93 goes like this, the dash unit in the front that has the Cassette, and control function. The tuner is in the trunk at the base of the wheel well, there is a large din that connects these two. If you have the CD it is first routed thru the CD before it goes to the tuner, the CD gets its power thru a "Y" from the tuner. The antenna goes to the tuner, most likely it has a splitter that allowed the analog phone to use the fendr mounted antenna. The 7 channel amp in the trunk drives 11 speakers, 2 on each side in the front doors (4 ohms I think) in enclosures, one each side in the rear doors (4 ohms I think), a tweeter behind the rear view mirror (who knows), and two speakers on each side on the rear deck (2 ohms each tied in series) for bass. The tuner outputs go to the Bose amp (top of wheel well driver side) which is controlled by the fader on the console, and the right to left is controlled by the dash contol unit, The two outboard speakers were for the Cell Tel audio and served no other purpose and were powered by the Cell Tel and fed by one pair terminated in the trunk area. The radio was muted by the Cell Tel. The antenna was raised by either the radio or the Cell Tel.
I think you have a interesting journey making sense of the speakers and the associated wiring