Many, MANY, MB owners and enthusiasts (outside the US) refer to a W123 300CD Turbodiesel as a 300CD-T or 300CDT basically to distinguish the car as a Turbodiesel vs. Diesel (non-turbo). In fact when I had my euro-version 1984 300TD Turbodiesel, I often had to refer to it as a 300TD-T (or 300TDT) since a euro-spec W123 wagon was available in both turbodiesel and non-turbo variants in model year '84 (from Germany). You'd be surprised how many people outside the US refer to the W123 Turbodiesels as CDT, TDT, etc...
Many of us know the CDT or TDT isn't the correct nomenclature but I certainly don't have anything against it since the seller (hopefully) stated it that way in order to distinguish it as a true turbodiesel model. Hope this helps in any way... to a "T"
