If you know exactly what it came out of, I'm sure the schematics will be easy to find on the net. I have in the past done this with other head units.
Any info on the other tag on the top? Any numbers stamped on the bottom?
Factory units as far as I know, the security system can not be disabled.
You might have to take it to GM (I assume it's from a GM) Looks like one that was in an older Sierra I owned.