VT 100CS

I have a gamma head unit (Bose) in a 1992 100CS. It has recently started making a buzzing sound in the rear deck that is almost unbearable to be in the car with. It is unrelated to the volume **** setting, the level is always the same. I would like to replace the gamma head unit with a CD player, while at the same time keeping the display between the tach and speedo. I would appreciate suggestions, thanks.