The fiber optic ring was introduced about MY2000 (?) and the old and new radios/changers are largely incompatible. For that radio you will want a changer of the same vintage.

Although you didn't ask, why stay with a changer that only has 6 disks, requires you to stop the car to change disks and frequently doesn't work. Have you considered adding a AUX-IN cable to the changer output of that radio and using an MP3 player? Essentially unlimited music on something smaller than a Smart Key.