I bought an aftermarket reciever made by dual(Dual XDMA6415 200-Watt AM/FM/CD/MP3/WMA Receiver with Built-In Bluetooth (Black), for my older MBZ, and it connected perfectly. I stream google music, pandora, makes calls, everything I wanted, and the deck only cost me $69(orig $249) on amazon. Some of the features I like, I can answer calls from the reciever, use the keys to forward tracks on both google music and pandora. It also comes with a remote.
One side note. It said on amazon that it would not fit my car, for what ever reason I ordered by mistake. Good thing I was too late to cancel my order. Because I'm a prime member I don't get a lot of flack for returns. When it arrived i found that it indeed would fit, bought the harness(wire adapters) I needed and an antenna adapter. All is good. Great for anyone who has an older car without Bluetooth. and I don't work for dual, as a matter of fact haven't installed a car stereo since high school, figured it would be like putting in a video card..yep, that simple.