M-21 Overdrive Gearset - Pontiac GTO Forum
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post #1 of 2 (permalink) Old 05-03-2017, 03:19 PM Thread Starter
 
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M-21 Overdrive Gearset

Couple years back there were gearsets that gave the M-21 an overdrive. Basically 3rd gear became the overdrive and then you flipped the shift lever and basically swapped the shift pattern between 3rd and 4th. these still available? anyone have any experience with them?
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post #2 of 2 (permalink) Old 05-03-2017, 05:23 PM
 
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Originally Posted by Brad3112 View Post
Couple years back there were gearsets that gave the M-21 an overdrive. Basically 3rd gear became the overdrive and then you flipped the shift lever and basically swapped the shift pattern between 3rd and 4th. these still available? anyone have any experience with them?

Sounds like a trucker tale to me, that's what you do with a 9 or 13-speed - flip the top gear which makes for a reversed gear pattern. Takes a while to get used to the "U-pattern" vs the typical "H-pattern" shifting.

For the Muncie, Beaver Brook offers the gear cluster to do this, $795.00. They still show it in their catalog: Beaver Brook - Muncie Transmission Parts

From what I have read about them when they first came out, you basically are turning your transmission into a 3-speed with OD.
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  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, Lemans & GTO Undercarriage, Frame, Transmission and Differential Discussions.

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