I'm restoring a 1971 442. I bought a roller with the 4 speed hump, no tranny or engine. I have the engine (year correct, non #s matching 455).The rear end is a 3:90 posi with stabilizer bars. I've gotten differing opinions on the "rock crusher" and on the M21. What do the experts think ?

 

the gearing is the same between the M-21 and the M-22. it is just that the M-22 is stronger and will cost much more. the M-22 also requires the yolk the same size as the TH400.

 

Taking money out of the equation, which do you prefer?

 

M22 bar none. I love the sound it makes. Shifting threw them gears. With real olds power. Nothing better than that.

 

Nothing is better than the M22. I have M22 in my car! You can also have a 10 spline small output M22, or fine spline small output, or fine spline large output. It depends on what you want, and your budget.

 

The m22 is much stronger and they don't call it the rock crusher for no reason, they are noisy.

 

Well, the experts have spoken and it seems we have a concensus. The search begins as does the second mortage application. Thank you for your input gentlemen.

 

M-22 X-10!! Only trans that could put up with powershifts, and last!!
I've broke 1 - T-10, 3 - M-20's, 2 - ST-10's, and a couple M-21's in my lifetime, and never had the slightest problem with a M-22!
Output shaft varies with the year, as they were constantly upgrading!
The 'new' ones would probably last forever, with all the beef built in!
There's another thread running right now, showing the difference.

 

If you are wondering what came in the car originally,it was either the M20 or the M22.That os what was offered in the Cutlass/442 for 1971.In 1971,the M20 got the fine-spline input,and large output,just like the M22.Basicly,they looked the same on the outside,but the M22 had the straighter-cut gear cluster.

 

Today, Auto Gear is building stronger Muncie type transmissions, and you can get more ratios. The problem with the M20 was the big gap between 3rd and 4th, where your engine could least take it. The big gap should be 1st to 2nd, then progresively smaller. When you are done buying an Auto Gear or other M22, you will be about $2K into it, and that puts you 2/3 of the way to the Jerico. You WON'T break the Jerico, can choose any ratios, and can get road race sliders so it will shift smoothly and be easily downshifted. My Jerico has 3.08, 1.93, 1.34, 1:1 ratios. NHRA stockers get 3.17 to 3.29 first gears these days. You can get it in early Muncie length (1/2" shorter than late Muncie/current Super T10) or 3" longer. The latter lets you have a shorter driveshaft for a higher critical speed.