05 radio swap

I have a 05 1500 I just have the am/fm radio I am going to swap it out for a cd player. Is there anything special I need to do what is this RDS thing I have read about. Thanks

if you get a gm stereo from a junkyard or e-bay you don't need that thing but you'll need a dealer to unlock it with a tech2.

I am not going to use A gm radio. I am using aftermarket.