2003 radio question

I have essentially a baseline 2003 silverado which came with just the AM/FM radio. I'm interested in putting in a stock CD/Cassette/Radio. I've been keeping an eye out on Ebay for one. Does anyone have other/better sources for a used one? Also if I find a unit that is for a 2003, other than the Bose option which I know won't work, will the RDS units plug into my harness? The local dealership's parts department seems rather clueless when it comes to what will fit and what will not. I do want to stick with a delco unit.

Thanks for your help.

I also have the same kind of truck, and am replacing the same kind of radio with a CD player. Did you find that you had to go to the dealer to find what kind of Delco CD players were compatible ? I can't seem to find a website that would tell me which Delco units are compatible.
Emal me at trl5@charter.net Thanks

All the trucks I've ever seen, if you can find a stock delco CD reciever, it should replace the one your taking out perfectly. I'm not sure about '03 though.

the 03 did change, anything previous from the factory won't plug in, as for aftermarket, there is not a switched twelve volt power lead at the deck. if you have onstar or bose you'll need an adapter for those too. A company called peripheral should have your adapter for you, and you'll still need an antenna adapter also. the parts can add up quick, so i could see where the 150 bucks would come into play

Probably the biggest problem you will run into when trying to put another stock stereo in is that the anti theft system will disable the replacement deck. Starting in 2003 on the Silverados, the Vin code is stored in the stereo and will only work if it match's the vehicle it is in, if not it locks the deck and you have to take it to the dealer to unlock it.
You would be better of getting an aftermarket deck with the right adapters to install it.