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That is something I have never seen before. Very interesting. It looks like it has GM radio plug adaptors on it. So you can hook it and loop the signals through. A few of those plugs you are holding in the dash are factory radio plugs. With all that masking tape on the chips I would bet that is the product of a small company made to interface the Bose radio to something else...or the Bose amps.
I see you have an alarm to contend with also....must be having alot of fun. lol
good luck, your going to need it
PS If I was in your shoes, I'd take my voltmeter and test each wire. I would go to ground first and see if the wires are 12 volt or ground (use DC and ohm setting) Then I would turn on the car and check the wires for 12 volts to see if any are wired to the ignition. There might be a ignition ground but that would be extremely rare
The car used to have an alarm on it but it does not get driven enough and kept killing the battery so it got pulled. I finally dug up the information on the owner who installed the stereo. I have been trying to get in touch with him all day.