This downflow replacement radiator is made from high-quality aluminum, is newly designed, and improves the performance of your manual transmission 1965-1966 Mustang across the board. With extra-large, 1-inch tubes for 4-row-style efficiency, your engine can cool much more efficiently than the restrictive OEM style copper-brass radiators. The aluminum design has shaved off 5-7 pounds in comparison to the factory OEM radiator. The OEM radiator is known for its issues with uneven distribution of hot water across the top of the radiator. This radiator has redesigned piping within their radiator to evenly distribute the hot water coming off the engine, enabling the entire radiator to be used to cool your engine. Radiator cap sold seperatly.