A transmission rebuilder is a specialized mechanic who handles the maintenance and repair of vehicle transmissions. As a transmission rebuilder, you typically operate in a body shop and work with standard mechanic tools to service cars. Your responsibilities are to diagnose vehicle transmission issues, rebuild transmissions to manufacturer specifications, and ensure these systems work efficiently and effectively. You handle gears, clutches, and other parts to assist with the recreation of the transmission, as well as properly remove and reinstall transmissions. Other duties involve maintaining the cleanliness of your area and tools.