contact RB Vintage Radio in Mt. Juliet, TN. They will take your original radio and use U.S. made components to give you AM/FM, bluetooth, AUX, etc. (you choose what you want).
The quality of his conversions leave the "other two" (that use Chinese-made components) in the dust and your radio still looks like GM intended.
http://www.randbvintageautoradio.com/