GM reference part numbers: 340637, 340638. Designed as the. C3 Corvettes with carbureted engines: 1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982. Fits the Following Corvette Models outer blue spring, it provides the correct tension and response Chevrolet engineered for consistent drivability and safety.