2004 sierra crew cab LS. How can I wire in a mini phone jack so that I can take the audio from a portable dvd player to output on the existing radio and speakers? My radio has a CD/Aux button. It's the radio that comes with the LS model, single CD with radio, nothing fancy.I pulled the radio out. There is a C1 connector with the speaker wiring and power. There is nothing connected to the C2 spot on the back of the radio. Is there an add on box with a mini phone jack or even RCAs? Can I buy a plug and make my own? Any suggests?