2002 Denali

I have a 02 Denali and jsut put in a new Nav System and so the 6 disc changer does not work anymore and I am wondering if there is something that I can replace it with. I wouldn't mind just having a slide in Din Compartment but the GMC dealer gave me model number 15958735 and it wont work. Does anyone have any ideas or know the part number for the appropriate Din for the 02 Denali?