I used to have an '01 Malibu. I had installed a soundsystem in there (new head unit, 2 12's, 2 amps, new speakers) but needed to keep the old cd player in the trunk with an adapter because the brain of the car was held in there. I guess it had some kind of thing that, if the cd player was stolen from the car, the car would shut down and not work. Apparently Chevy started doing this back in 2000 or 2001. I have since upgraded to an '07 Colorado, and it too has a stock stereo in there. I was wondering if Chevy still did this. I would like to get a new head unit for my Colorado, and would like to reinstall my old system into my truck, but I don't have an owners manual (where I originally found this out for the Malibu). Does anybody know anything about this? Any Colorado owners that can relate to this question? Thanks.