Ford Mach 460 - 2001 - clarification needed?

My dad bought a used 2001 Ford Mustang GT convertible that was optioned with fog lights, traction control, and the Mach 460 stereo, but the head unit had been replaced prior to our ownership, and the two gray cables had been cut. We have a head unit from another 2001 Mustang that we were planning to install, but it is the standard din size which had a separate CD player below it, and has a single gray cable to the amps. Apparently, cars optioned with fog lights and traction control had a different double din deck to accommodate the switches in the dash, and it appears they had different cables too. I have seen schematics that show the double din deck had three wires to each amplifier mounted in the trunk - audio +, audio -, and switched power, with one wire not used. I've also read that the four small speakers were powered by the head unit, but I've also read that there is a third amplifier on the transmission tunnel, which is what I believe we have. When I look at the clipped cables and mess of wires in my dad's car, I can't see how audio went from the double-din deck to the amp or speakers. If the 2 gray cables with 4 wires each were only used for the rear amps and sub woofers, then how did the double din deck get sound to the 4 speakers? The standard din deck has a six pin cable for the external CD player, and an 8 pin cable for all 8 speakers. The speaker count is the same, but the wiring is different, and that's what I'm trying to figure out. I think that a lot of the information I've come across has not made a distinction between these two head units. Does anyone know more about the wiring on these than I do?