Stereo Madness?
 

When I bought my new to mexg it came with a cassette jammed in the tape deck. I'm trying to decide whether to get a used one out of another 03 or get a 1 din replacement with a more current feature set. I hear the factory radios can be different so you need to look for one in use when your car was built and all need programming at the dealer. any truth to this? if so can I even swap in a new modern stereo instead? There's no getting the tape out of the deck currently in the car. as always any help is greatly appreciated. Thanks

If your vehicle is an 03, it probably has a "CAN" network. CAN= Controller Area Network
Some networks incorporate the radio as a module in the network. If this is the case, your options may be limited since the network may not function as designed and can even prevent the vehicle from starting if this is how it was designed. I would suggest that you get as much info regarding this as you possibly can before spending a lot of $$$ on something you may not be able to install.

looks like there's a code involved and it may also require a head unit made before a certain time in 03. Can anyone confirm that the code is the last 4 of the unit serial no. + 1212? or the head unit dating thing?

Most times a dealership parts dept has that info. If you can't get it here try the dealership.