You can get an fm modulator for any of the mp3 players... I know ford has mp3 but i dont know if gm does.

food for thought- alpine Hu's (well some of them) are able to contol an ipod, so you can put your ipod mount in the glove box or center console.. and never have ot look at it to change songs

much better imho than the 1000$ + price tag of the HD based head units