What are the factory specifications (gear ratios, etc.) of the Muncie M-22 4-speed installed in the 1970 LS-6 Chevelle? The reason I ask is I would like to purchase a new M-22 from a company over the internet (https://www.5speeds.com/store/html/4speeds.html), though there are some options buyers can select. I would like to get an M-22 that is set up exactly the way it would have come from the factory in an LS-6 Chevelle. I understand the reasoning behind purchasing other types of transmissions or even modified versions of the M-22 design (wider ratios, etc.) that modern companies offer, but I would like to stay faithful to the original specs :)

Thanks.

On a real M22, the first gear ratio is 2.20:1

Off the top of my head, the 2nd gear ratio I believe to be 1.64, 3rd is 1.28 and 4th is 1:1.

There are only 2 gearset ratios for the Muncie, depending on the years, the M20 wide ratio 1st gear is 2.52 or 2.56, and M21-M22 1st gear ratio is always 2.20.

Yes, 2.20 is the ratio used in the original M22. There are different after market ratios, M22W, and M22Z offered by Auto Gear and sold by 5speeds.com, and others, as you already know.

Also, the 1970 M22 introduced mid-model year for the 454 applications used the 26 spline input and the 32 spline output. The earlier M22s used the 10 spline input and 27 spline output.

Dave is right on the gear ratios.

Hi there. Does anyone know when they switched over to the big spine input/output? I have a real '70 LS6 built on Dec 22nd 1969 and wonder if it should have the course 10 spline or fine 26 spline? Great forum. Thanks in advance!

Rob,
All 70 LS6 cars got the 26 spline input with the 32 spline mainshaft regardless of production build date. If you have a buildsheet for your car the trans code should read WO which is the broadcast code used on 454 Chevelles in 1970. The WO trans is part # 3978766 and was indeed a 26 spline input, 32 spline output M22.
Hope this helps, Chris

Chris, THANK YOU!! I just checked my build sheet and verified in box "28 Trans" is a WO.