here is what to do if you want NAV. the only parts you will need is the NAV radio and the GPS module which will go underneath the panel by the defrost grille (it will already have a bracket there for the GPS module) the GPS is about $100. now the only way to get a part number for a NAV radio is you are going to have to find a 2008 module with the NAV radio, take that VIN number to a GM dealer, then have the tech at the GM dealer to program your radio with the RPO codes from that VIN. thats all you need to do. good luck. and please accept my answer. thanks T-MAN
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