Tayman electrical will set you up real nice if you have the money to spend on updating an original radio. I sent him my radio and he updated it with a modern digital am/fm tuner. The radio now has output jacks so I can run a seperate cd player or I can wire in a mp3 player.
For now I am happy with running my XM hidden in my glovebox through the radio. Everything looks stock but wow it sure plays like a newer radio. I also added two 6x9 speakers behind the seat for some extra sound at highway speeds.
Check my webhosts link for the radio photo album for photos.