Muncie M-20, m-21, of M-22?

What's the diff? I've got a 53 extended block 331 Hemi and I'm thinking the M-20.

What do you think?

 

M20 is wide ratio, M21 is close ratio, M22 is heavy duty close ratio. M20 should be fine for your application.

 

I notice the M-21 seems too be the cheaper of the three.
Anyone know why?

 

Not sure I've found M21s as cheaper. I use Muncies for race cars, and am always looking for M21s and M22s. M20 has a 2.52 low gear, while M21-22 has 2.20 low gear (other ratios spaced accordingly). M20 better for heavy car or street use with low (numerical) axle - M21-22 better for race track with high axle ratio. M22s are like gold now, since restorers of muscle cars are bidding them up.

 

M-22 AKA the "rockcrusher" is basically the heavy duty version of the M-21 with its notorious straight cut gears. I heard you can make one from the case of certain M-21's. There is an Italian company that was re-making the gears, even a set that had a fourth gear with an overdrive!

 

I'll be running the Muncie with a 70's ford truck 9" rear end.

 

M-22 is costly but great if you can afford one. It will handle more power and has a distinctive whine. I got a Super T-10 with the 2:88 first gear. Love this trans.

 

Given the cost of the hemi adapters the couple hundred extra for a good used M22 is money well spent IMO. They'll all do the job, as will a super T-10

 

I think I'll be going with the M-21. E bay has great prices on the M-21 they seem to be cheaper than the others.

 

I just won a Muncie M-21 off eBay for $531.00 with a Hurst comp shifter and linkage.

Now I'll need to find an adapter for my 53 331 extended block Hemi

 

Thats a good price but remember muncie's aren't unbustable, super T10'S are the hot ticket if you are going to lean on it. The 2.43 first are the toughest!

 

It's going in a 27 Dodge 4 door sedan. I don't think I'll be leaning on it too hard.

 

I'm kind of biased toword the A833's. They're pretty hard to bust.

 

Does anyone know of a good book showing how to overhaul these transmissions?

 

M-20-wide ratio
M-21-close ratio
M-22-don't worry, you prolly won't find one. I've seen less than I can count on one hand in 30 year

Externally-all the same as far as fitment

 

You can tell m-20 & m-21 from the rings on the shaft, I believe 20's have one ring & 21's have two. Always be wary of someone selling you a 22 “rock crusher” As the post earlier said, I’ve seen hundreds advertised but in reality I’ve only seen one in person all m-22’s have the bigger yoke (same as a t/h400) but so do some 21’s. There are some companies selling m-22 conversion kits so we’ll probably start seeing more out there. $500 bucks is a fair deal, seems like you can’t touch a core around here for under $700… Just check the ears as they seem to crack a lot. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

 

Yes I've heard.

Thank you

 

Hey man..
I think you got a great deal!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

I found this site to be very informative.

http://www.gearzone.net/muncie.htm

 

Yes
Thank you this is a good site.

 

Beef it up or buy a new one from Auto Gear...

http://autogear.net/muncieproducts.htm

 

Ratios of the M20 , M21 , M22 <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>​

Year 1963-1965 Type: M20 Rings: None Ratio: 2.56 / 1.91 / 1.48 / 1.00 / 3.16<o></o>
Year 1966-1974 Type: M20 Rings: Two Ratio: 2.52 / 1.88 / 1.46 / 1.00 / 3.11<o></o>
Year 1963-1974 Type: M21 Rings: One Ratio: 2.20 / 1.64 / 1.28 / 1.00 / 2.27<o></o>
Year 1967-1974 Type: M22 Rings: None Ratio: 2.20 / 1.64 / 1.28 / 1.00 / 2.27