# '64 Muncie M-20 for a 1966 GTO?



## Joes1966GTO (Apr 27, 2020)

Hi Everyone. I'm looking at purchasing a good quality M-20 for my 1966 GTO, but have two questions that are a bit above my pay grade:

-Does anyone know of any issues with bolting up a '64 M-20 to a '66?

-What's the best approach for purchasing linkage and a shifter? Purchase for a '64? or '66? Or are they all the same?

Any advice would be greatly appreciated.


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## Old Man Taylor (May 9, 2011)

There's no issues with bolting it up. As to the shifter setup, it won't make a difference if you don't have a console. I'm not knowledgeable about the fit in a '66 with a console.


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## BLK69JUDGE (Jun 10, 2010)

my .02
the 64 muncie is a 1 year wonder 64 65 w 325 case 
with the front bearing retainer being smaller and wont fit correctly on your 66 bellhousing then you will need the dorky 64 small hole B housing with its
no lower pressure plate bolt access bellhousing OR use the spacer ring that likes to fall out ...

dont use 64-66 linkage spirited shifting they go out of adjustment often
do your google images homework ,,,, poor clamp style design revised for 67

use a 66 shifter but hang 67 68 linkage on it

try n stay with a 67 68 tranny ,,, w 660 or 661 case

, 69 has a linkage lever change
and the 70-72 up muncie things change again clutch disc ... output yoke ...shifter mount plate... length ...



Scott


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## Old Man Taylor (May 9, 2011)

The bearing retainer is the same size. I've run many different Muncie's in my car ('64 GTO) with no problems. The issue with the early M-20's is the diameter of the cluster pin (countershaft). It is 7/8", whereas they changed to 1" in 1966. The smaller pin is more prone to egg shaping the case. However, my car had the '64 trans in for about 10 years with no problems. Then I put good slicks on the car. After one year the pin was quite loose and I upgraded to a later trans. You do have to watch out for the spline count on the input shaft. The early trans had 10 teeth, the later ones had 26 (called fine spline). I don't think they started the fine splines until 1971, except for the M-22. If you change spline counts then you have to change your clutch disc.


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## Daryl (Aug 15, 2020)

I have a 66 LeMans and did a body off restoration a few years ago and mounted the engine on the frame before the body went on. I switched over from the 2 speed automatic to a M-20 Muncie out of a 67 Camaro, so I had to build and setup the clutch linkage. (Needed to purchase new clutch, used pressure plate on Craigslist and used bell housing on ebay) It went together but was tight. I have Hedman headers as well and they fit ok since the body was off. It all went together but was tight fitting everything. The issues I'm having now is that I have to pull the 326 out due to a spun bearing on the crank-piston rod and have to try to get everything apart. The passenger side was a breeze, but the drivers side is a royal pain. The main thing that is in the way is the driver side header. It's so difficult to remove everything and now I'm considering replacing the headers with stock exhaust manifolds just to be able to put the car back together after the engine repairs.
So to answer the main posts question is that parts are available but when I bought the used tranny it had the hurst linkage included. The internals were destroyed so it needed a complete rebuild. 
I'm wondering if anyone has clearance issues with clutch linkage and stock manifolds or are they as bad as cursing/working with the Hedman headers? If anyone has an old set of exhaust manifolds for a 326 or 400 pointiac, I would be interested in buying them. Thanks Daryl


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## Daryl (Aug 15, 2020)

Joes1966GTO said:


> Hi Everyone. I'm looking at purchasing a good quality M-20 for my 1966 GTO, but have two questions that are a bit above my pay grade:
> 
> -Does anyone know of any issues with bolting up a '64 M-20 to a '66?
> 
> ...


Check with Summit Racing or YearOne for the clutch linkage. The pressure plates are sometimes difficult to find but clutches are very much available from many sources. Hurst makes good shifter linkages so check with Summitracing for them. I found a good bell housing on ebay but you might get some information about fitting the M-20 from Muncie 4 Speed Transmissions and Parts
Good luck


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