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    Fuzzy match across codes, option descriptions, and model aliases. Every result is graded and, where the factory documents it, cited.
    M21 Factory-verified

    Chevrolet · Regular Production Option

    4-Speed Manual, close ratio

    Years 1963–82 Models 6 Factory citations 24

    Also described as 4-speed manual, close ratio4-Speed Transmission - Close Ratio4-speed manual, close ratio (L82 only)4-speed close-ratio manual transmissionMuncie 4 speed close ratio transmission4-speed manual transmission - close ratio

    Documented applications

    Camaro
    • 1967–1969 Factory-verified

      Z28/L34/L78

      GM Heritage factory kit — 1967 Chevrolet Camaro, p.51.
      GM Heritage factory kit — 1969 Chevrolet Camaro, p.47.
    • 1970–1974 Factory-verified
      GM Heritage factory kit — 1970 Chevrolet Camaro, p.9.
      GM Heritage factory kit — 1974 Chevrolet Camaro, p.8.
    Chevelle / El Camino
    • 1966–1970 Factory-verified
      GM Heritage factory kit — 1966 Chevrolet Chevelle, p.96.
      GM Heritage factory kit — 1970 Chevrolet El Camino, p.3.
    Corvette (C1 / C2)
    • 1966 Factory-verified

      $184.35; 13,903 built

      GM Heritage factory kit — 1966 Chevrolet Corvette, p.14.
    • 1967 Factory-verified

      $184.35; 11,015 built

      GM Heritage factory kit — 1967 Chevrolet Corvette, p.57.
    Corvette (C3)
    • 1968 Factory-verified

      $184.35; 12,337 built

      GM Heritage factory kit — 1968 Chevrolet Corvette, p.7.
    • 1969 Factory-verified

      $184.80; 13,741 built

      GM Heritage factory kit — 1969 Chevrolet Corvette, p.5.
    • 1970 Factory-verified

      $0.00 (no cost); 4,383 built

      GM Heritage factory kit — 1970 Chevrolet Corvette, p.5.
    • 1971 Factory-verified

      $0.00 (no cost); 2,387 built

      GM Heritage factory kit — 1971 Chevrolet Corvette, p.6.
    • 1972 Factory-verified

      $0.00 (no cost); 1,638 built

      GM Heritage factory kit — 1972 Chevrolet Corvette, p.5.
    • 1973 Factory-verified

      $0.00; 3,704 built

      GM Heritage factory kit — 1973 Chevrolet Corvette, p.24.
    • 1974 Factory-verified

      $0.00; 3,494 built

      GM Heritage factory kit — 1974 Chevrolet Corvette, p.7.
    • 1975 Factory-verified

      $0.00; 1,057 built

      GM Heritage factory kit — 1975 Chevrolet Corvette, p.7.
    • 1976 Factory-verified

      $0.00; 2,088 built

      GM Heritage factory kit — 1976 Chevrolet Corvette, p.22.
    • 1977 Factory-verified

      n/c; 2,060 built

      GM Heritage factory kit — 1977 Chevrolet Corvette, p.48.
    • 1978 Factory-verified

      $0.00; 3,385 built

      GM Heritage factory kit — 1978 Chevrolet Corvette, p.22.
    • 1979 Factory-verified

      $0.00; 4,062 built

      GM Heritage factory kit — 1979 Chevrolet Corvette, p.7.
    Nova / Chevy II
    • 1966–1967 Factory-verified
      GM Heritage factory kit — 1966 Chevrolet Nova, p.21.
    • 1968–1970 Factory-verified
      GM Heritage factory kit — 1968 Chevrolet Nova Coupe, p.9.
      GM Heritage factory kit — 1970 Chevrolet Nova, p.59.

    Related codes · mentioned in these notes

    L34L78Z28

    This page aggregates every documented appearance of M21 in the Chevrolet reference. Confidence and citations are shown per application — the same code can be better documented in one year than another.