ive got a 1998 r129 sl500 and it currently has a tape holer built in the center compartment,does anyone know if i can replace this with a standard compartment?

 

Yes you can.
I replaced my tape unit with the Mercedes compartment. It cost about NZ$75.00. I just ordered it through my dealer.
You have to pop up all the tapeholders then you can pull the tape unit out.
The new compartment is just a square box, lined with black felt but it works well as a large cup holder (big enough for a take-away coke) because the base is level.
Unfortunately it does not include an internal light so the light that illuminates the tapes becomes useless. I am thinking of
modifying it slightly so at least the light will illuminate the interior.