Mucie 4-Speed casting 3925660

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Mar 1, 2011 | 05:53 PM

ittybittyfds

Thread Starter

Newbie

Joined: Apr 2010

Posts: 18

Mucie 4-Speed casting 3925660

how do i determine if 4 speed is a M20, M21 or M22
its casting is 3925660
after researching the casting it appears that the code is the same for all 3
Casting: 3925660 Years: 1968 - 1970 Ratios: M20 2.52 1st , M21 2.20 1st, M22 2.20 1st

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Mar 1, 2011 | 07:25 PM

dynarider33

2nd Gear member

Joined: May 2008

Posts: 428

From: Sneads Ferry, NC

Look at your input shaft. M20 has two grooves on it, M21 has one groove on it, and M22 has no grooves. This is assuming of course it has never been taken apart and changed.