Different type of plug. For some radios the plug alone can be $50. If you aren't going to use cd's anymore, I'd by the cheapest compatible model of the brand that I'm most familiar with.In crutchfield magazine, there's a Sony with built in Ipod control,remote, and sub control among other things for $160. You could even find a Dual radio with built in Ipod control forAbout $130 at Wal-Mart