04 silverado stereo question

I'm looking to replace my 04 silverado am/fm with at least a cd(cd/cass) preferably but have a couple questions. I have been trying to find out if one from a 02 s10 will work but have been told it wouldn't. I assumed it was because the wiring harnesses are different. Mine has 1-24 pin and it had a 24pin/12pin but upon looking at units from 03/04 models they also have the 24/12 pin setup? Is the 12 pin for a cd changer or steering wheen controls maybe? And would it work in my truck with only the 24 pin harness plugged in?

I'm not really worried about the chime system not working if that's anything that matters, as long as the stereo does work:)

Thanks

Does it have to be a factory stereo HU? Why not an aftermarket one from Alpine or Eclipse or some other company?

Me, I would just go with a good aftermarket one...If your gonna go to all the hastle of taking it out, I would upgrade to one that plays cd/mp3's....Thats just what I would do

My g/f will be driving it more than me and she's the one that want's both cd and cassette but will settle for just a cd if she has to. Plus I don't want to spend too much money on one since we wont be upgrading the speakers or add a amp. So I figured the cheapest and easiest route would be a stock unit to just plug in.

Check out the Alpine 9843, it's $150 MSRP...may be able to get cheaper soon. It plays CD's and MP3 CD's...great little deck...and not to expensive!

NG

Yeah but those radios in the '03 on up are Class 2 DATA radios. It costs more to deal with them compared to the older ones. He'd be better off to just swap radios. He'll have to go to the dealer to have it unlocked though.

How much does it cost to have a stocker unlocked?

Also what is the difference between 02/04 radios? There is a 02 cd/cassette on ebay and a 04 cd/cassette and they look exactly the same, screw holes are the same and both have the 12/24 pin connectors. Is it something internal between 'em? I only ask cause there's a 65.00 difference in prices for what appear to be the same thing.

Check out the Alpine 9843, it's $150 MSRP...may be able to get cheaper soon. It plays CD's and MP3 CD's...great little deck...and not to expensive!

NG
The dealer unlocked mine for $60.