[737IP]

I am looking for a maincase for my M20 to replace one that is broken. My current maincase is a 3885010 indicating a 1 inch countershaft bore. My understanding is that the older muncies came with the smaller 7/8 countershaft. Today, someone told me that all M20's came with the 7/8 bore. Can someone set the record straight?

Thanks.

[Sauron67MM]

I am not a Muncie expert, I look to those with greater knowledge than I and file it.

Quoted from Jerry Macneish:

"The 3885010 case was used in 1966 and 67. One inch cluster pin, large syncro assemblies, the 64-65 Muncie ("325" case #) is a 7/8" pin with small shifting hubs and blocking rings. Bad design."

[HOGDADDY]

Originally Posted by 737IP

I am looking for a maincase for my M20 to replace one that is broken. My current maincase is a 3885010 indicating a 1 inch countershaft bore. My understanding is that the older muncies came with the smaller 7/8 countershaft. Today, someone told me that all M20's came with the 7/8 bore. Can someone set the record straight?

Thanks.

He's wrong!

[NHBandit]

63-65 are the only ones with a 7/8 shaft. There are no exceptions I know of and the guy who told you otherwise is wrong.

[hereitis67]

this will help you out
http://www.camaros.org/trans.shtml#Muncie

[hereitis67]

also if you need that case i have 1. pm me if you need it.

[737IP]

That's what I thought. Thanks for the quick replies.

[mrmuncie]

ebay is a pretty good place to find what you need. The cases with the one inch bore are 010 660 and 661. If your not worried about build code dates any one of these castings will be fine.

[Straight-line-69]

If you're building any HP at all, now would be a good time to go to the Muncie Super-Case from these folks:

www.autogear.net

[larryh56]

x2 on the super-case. I put one in my '69 and it is a MUCH better built case - better alloy, full size bearings on both ends, o-ring drain plug, etc. It has a slightly thicker front part so you gain about a 1/2 inch in length if I remember correctly.

[JodysTransmissions]

Yes, the Supercase utilizes a full width 307 front bearing for added strength too. No more leaks at the front countershaft either.

[737IP]

I have been watching these things on Ebay and for what they are selling for you are real close to a new supercase!

[JodysTransmissions]

Originally Posted by 737IP

I have been watching these things on Ebay and for what they are selling for you are real close to a new supercase!

Most used cases need to be machined for bushings at the countergear shaft to prevent gear lube loss. That service is about $150.00, well worth it if you have a numbers matching case to the vehicle. Otherwise, usually a Supercase is a better buy for non-matching number car.

Most times when you see a case for sale, that case came from an exploded gearset. That could also mean case stretch between the mainshaft and countershaft centerline and that is not good either.