Author Topic: M20 or M21  (Read 3056 times)

firstgenaddict

  • Hero Member
  • *****
  • Posts: 1941
    • View Profile
    • Groome Family Automobiles
M20 or M21
« on: August 13, 2008, 04:40:44 PM »
How was it determined whether a car got a M20 or a M21?
I am restoring a numbers matching 69 and the car has a 4.10 rear and numbers matching trans...
The stamp on the trans is correct with no A, B, C suffix... (Trans assembled October 19th 1968).
Who or what options determined the trans selection?

James
James
Collectin' Camaro's since "Only Rednecks drove them"
 
Check out the Black 69 RS/Z28 45k mile Survivor and the Lemans Blue 69 Z 10D frame off...
https://plus.google.com/photos/112392262205377424364/albums?banner=pwa

KurtS

  • CRG Coordinator
  • *****
  • Posts: 4771
    • View Profile
Re: M20 or M21
« Reply #1 on: August 13, 2008, 06:48:51 PM »
Depends on the car. An L48 or L35 could only come with a M20.

For a Z like yours, it was up to who ordered it.
Kurt S
CRG

firstgenaddict

  • Hero Member
  • *****
  • Posts: 1941
    • View Profile
    • Groome Family Automobiles
Re: M20 or M21
« Reply #2 on: August 13, 2008, 07:13:41 PM »
As in the customer or the dealer?
Why would this be left up to the dealer?
I thought it would have been rear end ratio regulated... as a M21 with 3.55's would be hell to drive...
James
Collectin' Camaro's since "Only Rednecks drove them"
 
Check out the Black 69 RS/Z28 45k mile Survivor and the Lemans Blue 69 Z 10D frame off...
https://plus.google.com/photos/112392262205377424364/albums?banner=pwa

JohnZ

  • CRG Member
  • *****
  • Posts: 4363
    • View Profile
Re: M20 or M21
« Reply #3 on: August 14, 2008, 04:45:04 PM »
As in the customer or the dealer?

It was up to the customer - he could order M20, M21 or M22. Although the 3.73 was the "standard" Z/28 axle if no other ratio was ordered, Chevrolet's AMA submission for the Z/28 option shows availability of the 3.55 as an "economy" option, the 4.10 as a "Performance" option, and the 3.07 as a "Special Order" option.

The 3.55, 3.73, and 4.10 were available with either M20, M21, or M22, but the 3.07 "Special Order" axle was only available with M20 (for obvious reasons). :)
'69 Z/28
Fathom Green
CRG

firstgenaddict

  • Hero Member
  • *****
  • Posts: 1941
    • View Profile
    • Groome Family Automobiles
Re: M20 or M21
« Reply #4 on: August 14, 2008, 05:45:25 PM »
So if a guy ordered a M20 with 4.10's... he knew what he was doing... right?
James
Collectin' Camaro's since "Only Rednecks drove them"
 
Check out the Black 69 RS/Z28 45k mile Survivor and the Lemans Blue 69 Z 10D frame off...
https://plus.google.com/photos/112392262205377424364/albums?banner=pwa

JohnZ

  • CRG Member
  • *****
  • Posts: 4363
    • View Profile
Re: M20 or M21
« Reply #5 on: August 15, 2008, 03:10:12 PM »
So if a guy ordered a M20 with 4.10's... he knew what he was doing... right?

That combo would definitely provide the best launch.  :)
'69 Z/28
Fathom Green
CRG