OK, I am currently restoring a 1969 Camaro and am putting a 4-speed in it. I don't know a lot about the 4-speed transmissions they used that year, only that they were the Muncie's. So, did they use all 3 of the M-20, 21, and 22, or did they only use certain a one (or 2) that year? Also, which one would be the best for a modestly built big block.?

 

All three were used; which one depended on the engine and diff ratio. A 69 SS could have an M20 if the ratio was 3.31, M21 if it was a 3.73. Factory tended not to use wide ratio (2.54 1st) M20 with the deeper gears, but special orders could have it. M22 was optional, rarely ordered.


Best for a mild big block would depend on rear end ratio, among other things. If you plan on using a 3.31 gear, wide ratio M20 would probably be best. Deeper gear, M21. If you can find an M22, grab it if price isn't outrageous.

 

OK, that makes sense. Thanks.

 

Looks like I'm gonna go with an M21.