Aftermarket stereo deck

I have an aftermarket stereo deck that i would like to install into my 04 grand prix but ive been told that i will need a special harness for this installation that costs over 100 bucks. Is there any way around this or do I have to buy the harness?

The radio is part of the diagnostic/information serial bus, and you will have to buy the radio relocator kit to install an aftermarket unit in that vehicle. The factory radio has to be left hooked up (hence the need for the relocator kit) for certain BCM and diagnostic functions, so it cannot be simply removed and replaced.

X2, seems i remember a relocation kit that could be bought so you could hide your old radio in the trunk. Check www.crutchfield.com