Thank you for your question. Any new Monitor 14 series shower trim will fit an existing 1400 series valve body. The new trim will come with a new valve cartridge assembly. This new cartridge will not work in the existing valve. You will want to keep your same, white cartridge. If you do need to replace the cartridge, you will want to replace with a RP19804 cartridge.
Date published: 2019-03-22