can I replace my 06 factory stereo for an 08 factory stereo?

long story short, I can't put an aux input in my 06 G6 stereo, no band or p-type button, and I don't want to use an FM modulator...can I buy a factory stereo off like ebay from an 08 or 07 G6 and use it in my car? And even if the plug fits, is the software used on the newer models possibly different? the dealership was clueless. any help would be great!