Concert 2+ (Double Size)
The factory wiring uses a Quadlock plug.
Models with this unit were either non-amplified, rear amplified or full BOSE amplified. You can identify BOSE by the speaker grills having the logo on there.
You can identify the system from the 8 pin speaker block in the quadlock. Fully pinned means non-amplfied, 4 pins means rear amplified and no pins means fully amplified.