M20 or M21 - NCRS Discussion Boards

M20 or M21

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • Leif A.
    Extremely Frequent Poster
    • August 31, 1997
    • 3627

    #16
    Re: M20 or M21

    Originally posted by Gary Beaupre (28818)
    In Noland’s chart I don’t find L79, with 3.36 posi, and wide ratio, M21. But in the last chart that Jack posted, that combination is there. My ‘66 has that combination. Did that combination disappear for ‘67? Or is Nolan’s chart incorrect?

    Gary
    Gary,
    For both '66 and '67 model years when ordering the L79 option you could get the M20 wide ratio transmission with either the 3.36 open rear as standard equipment or 3.36 posi as an option. When ordering the L79 option with the M21 close ratio transmission, the 3.70 open diff was standard with the 3.70 posi available as an option. When the M20 was ordered you could, also, opt for a 3.55 open or posi rear. When the M21 was ordered you could opt for the 4.11 open or posi rear.
    You could not get the 3.36 or 3.55 gearing with the M21 nor could you get the 3.70 or 4.11 with the M20.
    Leif
    '67 Coupe L79, M21, C60, N14, N40, J50, A31, U69, A01, QB1
    Top Flight 2017 Lone Star Regional

    Comment

    • Gary B.
      Extremely Frequent Poster
      • February 1, 1997
      • 7019

      #17
      Re: M20 or M21

      Thanks for the explanation.

      Gary

      Comment

      • Duke W.
        Beyond Control Poster
        • January 1, 1993
        • 15669

        #18
        Re: M20 or M21

        Originally posted by Gary Beaupre (28818)
        In Noland’s chart I don’t find L79, with 3.36 posi, and wide ratio, M21. But in the last chart that Jack posted, that combination is there. My ‘66 has that combination. Did that combination disappear for ‘67? Or is Nolan’s chart incorrect?

        Gary
        Wide ratio is M20, close ratio is M21.

        The WR (M-20) 4-speed with a 3.36 axle was likely the most common drivetrain for L-79 in '66 and '67. Download the information packages from the GM Heritage Web site. They have all the drivetrain charts and lots more.

        Duke

        Comment

        • Gary B.
          Extremely Frequent Poster
          • February 1, 1997
          • 7019

          #19
          Re: M20 or M21

          Thanks Duke. I corrected my above post so as not to confuse future readers.

          Gary

          Comment

          • Gary S.
            Super Moderator
            • February 1, 1984
            • 457

            #20
            Re: M20 or M21

            And my original drivetrain 67 coupe, made Sept 1966, with tank sheet (removed by me) shows 350/M20/3:36 posi.
            Avatar--My first ever vette, owned 3X since 1977, restored 1993-2024. Top Flight Award 9/14/24

            Comment

            • Gary J.
              Extremely Frequent Poster
              • April 1, 1980
              • 1241

              #21
              Re: M20 or M21

              Originally posted by Gary Seymour (7140)
              And my original drivetrain 67 coupe, made Sept 1966, with tank sheet (removed by me) shows 350/M20/3:36 posi.

              Comment

              • Gary S.
                Super Moderator
                • February 1, 1984
                • 457

                #22
                Re: M20 or M21

                Serial #1866, built 9/28/66
                Avatar--My first ever vette, owned 3X since 1977, restored 1993-2024. Top Flight Award 9/14/24

                Comment

                Working...
                Searching...Please wait.
                An unexpected error was returned: 'Your submission could not be processed because you have logged in since the previous page was loaded.

                Please push the back button and reload the previous window.'
                An unexpected error was returned: 'Your submission could not be processed because the token has expired.

                Please push the back button and reload the previous window.'
                An internal error has occurred and the module cannot be displayed.
                There are no results that meet this criteria.
                Search Result for "|||"