Purchased 07 charger R/T ,has the RAK factory stereo it says it is MP3 capable but owners manuel is not real clear on how it works there is no aux. plug for mp3 player can anyone help?

 

It just means that you can put a cd in the player loaded with MP3 files and the radio will read it.

Instead of burning an audio cd on your computer that you can only fit maybe 16 songs on, you burn a data cd leaving the music files in MP3 format and now you can put maybe 200 songs on a disc. The radio will read it just as a computer would.