In 1961, President Kennedy began to use a modified 1961 Lincoln Continental convertible, bodied by Hess & Eisenhardt of Cincinnati, Ohio. Code-named SS-100-X, the Lincoln was an open car, designed with a set of interchangeable tops, including a black formal-profile top, plexiglass roof sections, and a stainless-steel targa top for the driver's compartment. In presidential parades and motorcades, the limousine was often used as an open car (to avoid stress on the cooling system). In the open configuration, John F. Kennedy was assassinated in November 1963. Following the Kennedy assassination, SS-100X was initially investigated for evidence; in early 1964, the vehicle was released to Hess & Eisenhardt, effectively becoming remanufactured. Distinguished by a shift from navy blue to black paint and the permanent fitment of a roof, SS-100X underwent extensive security modifications, adding armor plating and bulletproof glass. Retired from front-line service in 1967, the 1961 limousine remained in service until 1977, used by Presidents Johnson, Richard M. Nixon, Gerald R. Ford, and Jimmy Carter. SS-100X is on display at the Henry Ford Museum in Dearborn, Michigan, along with the Sunshine Special.