I am in process of this change,, I am going with a alpine,,, I got the numbers at work but,,, I think they are chs635 with mp3 ($235) and I bought the conversion cables,,, 1 is a AInet convert $14.,,then another cable ($10) that plugs into it that allows connection to the stock cable in the trunk,, I don't have the alpine unit yet,,, sooo I don't know if it works,,, check the alpine web page and to a search for the right connection cables..
post above beat me,,, anyway use what he said,, but the cables are cheap if use the electronic's compare seach engine's