If I'm correct, there were two options, the Delco amp for just the rear speakers (you can see it right behind glove box, small square grey box), or the bose system (trunk mounted black box). Both had the quad rear speaker deck.
Main difference is how the wires were run. Bose, everything is run from head unit to trunk and from trunk to speaker locations. Delco amp runs from head unit to glove compartment location to speakers, and stock runs from head unit to speakers.
I know 100% the Delco one was offered as I've seen it in person, and 90% on the bose.
All that being said, it's possible to wire up any option from any stock model. I wired a non amp gt to full bose system with rear 12 disk cd changer. It's possible, but not fun.
