2003 911 C2 to C4 modifications?

I have a 2003 C2 Convertible. I want to add the rear red wideband refelector that you see on the new 2004 C4 convertible to my car. It seems that the rea deck lid on the C4 is slightly indented to accomodate the reflector and also the rear lights are curved. I have tried to contact a few dealers and they tell me that they are not sure if I would have to replace the rear deck lid and lights. Does anyone know what I need to do to add this reflector?