Been down this road on my 00 GT and the radio I swapped into my 95 Bonne to gain 7-band eq and CD player, as it had a tape player originally. I never had to get the unlock code for any of the radios.

The bulb is GM/AC Delco part #16208443, cost between $8-10
Here is a pic of the bulb too.
http://i28.photobucket.com/albums/c2...mradiobulb.jpg

And take a look at this post from another forum on how to replace it.---> Radio Backlight Lamp Replacement '97-'03 - Automotive Forums .com Car Chat