Thank you for your question, Donald! If you have a model T18255-RB installed, you will need to order a sleeve RP37901 to use the new trim as the stem of the new diverter cartridge will work in place of the stem assembly and extender. You will not be using the extender with the new cartridge however, this could require adjusting the rough-in valves in the wall, as the trims may not cover the existing hole and the one piece trim plate for the T18255 is only available in Chrome at this time.
Best regards, Edward
Date published: 2019-07-08