Delco MT starters are a series of high-performance starter motors made by Delco Remy for medium and heavy-duty applications like trucks, commercial vehicles, and industrial equipment. The "MT" likely refers to their "Medium-duty and heavy-duty" line, which includes specific models like the 39MT, 42MT, and 50MT. These starters are known for their durability and are designed to deliver strong cranking power, with some models offering features like gear reduction for faster cranking and integrated over-crank protection for durability.