According to my wiring diagrams, the two systems were "Two piece radio with sound system," and "Two piece radio with active bass." Both used an auxillary amp. The "sound system" uses aux amplifier to power all speakers. The "active bass" system uses aux amplifier to power only the left and right door speaker, which must be the sub woofer?? The rest get head unit only power.

Take a look for yourself, they're not easy to decipher. Wiring diagrams