Navigation system / Bluethoot

I have a Sierra 2008 that I would like to install a Navigation System ( Factory) in . What is involve in doing this? Any modification to be done?
If I only get a Radio replacement ( Factory)with Bluethoot is there major modification to be done?
Thanks Andre :screwy:

i have a 09 denali with factory nav and i hated it, you cant search destinations unless the vehicle is in park, and the screen is very low quality. mine does not have a usb port, and you cannot sync music via bluetooth. Sooo i would recommend going to an aftermarket brand like alpine etc. lots have bluetooth built right in so there is no need for extra interfaces. so you will just have to run the atenna wire to the roof of your vehicle. you can buy either a 1 din flip up monitor or 2din model. and to hook it up just buy the adapter wiring harness for your specific vehicle and a adapter face plate. these systems can range from 500 to 1500 bucks depending on how serious you wanna get. hope this helps