03 radio upgrade ?

[ictfooser]

I've got a basline 03 GMC Sierra, with just the basic radio without theftlock. I want to upgrade to a single disc with RDS. I have found a couple, but after talking to my local dealer, they tell me that they do not think that my pickup will support this radio, but I can bring it to them and they will program it for $45, cause they have to hook up the computer to it. If I get one without RDS I can use the press and hold 2&3 buttons programming trick, myself. I would like to have one with RDS, but I dont want to spend the money only to find out it will not work for me. If I get one without RDS will it work in my truck, without having to take it to a dealer to have it programmed? Also, will any 03 and up factory GM stero without RDS work in this truck, or does it have to be one specifically for trucks?