Transmission swap - Muncie M21 to New Process MY6 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Greg63 · 09-02-2013, 10:34 PM

I am wanting to get into an o.d. for my '63 and am thinking of swapping my M21 for an MY6.
The ratios for the Muncie are 2.20, 1.64, 1.28, 1.00
The ratios for the New Process are 3.09, 1.76, 1.00, 0.73
The two tranny's are physically identical, as are the input and output shaft sizes and splines so clutch swap and driveshaft work are not needed. Shifter location may be an issue.

I am looking for anyones experiences. Maybe someone here has done this swap already. Just looking for any other input.

Greg.

geezer#99 · 09-02-2013, 10:52 PM

Pm Keith Seymore. He has a factory installed one in his truck. He could answer your questions.
http://67-72chevytrucks.com/vboard/member.php?u=56854

**Captainfab** · 09-02-2013, 11:21 PM

I believe there are a couple members on the '60-'66 forum that have installed the MY6.

D13 · 09-03-2013, 06:56 AM

Input shaft retainers on the A833 (which is the trans for MY6) is a different size (except for a very few) which means you will have to have the A833 specific bell housing, and make sure you get the one for the correct style clutch (manual or hydraulic). Also MY6 shifters are unique (your Muncie won't work) and new ones are not available, so be sure you have the right one. They also appear to be different 2wd/4wd but probably either would work. There are a couple threads about them on the board, either here or in 73-87 section.

jjzepplin · 09-03-2013, 07:52 AM

How much for that m21?

Greg63 · 09-03-2013, 03:19 PM

Quote:

Originally Posted by D13

Input shaft retainers on the A833 (which is the trans for MY6) is a different size (except for a very few) which means you will have to have the A833 specific bell housing, and make sure you get the one for the correct style clutch (manual or hydraulic). Also MY6 shifters are unique (your Muncie won't work) and new ones are not available, so be sure you have the right one. They also appear to be different 2wd/4wd but probably either would work. There are a couple threads about them on the board, either here or in 73-87 section.

Good to know.
Greg.

Greg63 · 09-06-2013, 01:53 PM

Found one!
Aluminum case, shifter & linkages, plus shifter handle.
Also, the front bearing retainer fits my bellhousing hole.

My next project will soon be under way.
Greg.

Greg63 · 09-11-2013, 06:43 PM

In and done.

Pretty straight forward swap for me. The front bearing retainer fit right into my truck's bellhousing. It may have been turned down, but I didn't have to get it done. I spent most of my time with the MY6's shifter - cleaning out the old grease and removing the shifter handle.
I like the way the truck lopes along at 60 mph now.

This was a good swap.
Greg.

09-02-2013, 10:34 PM	#1
Greg63 Enjoy your truck Join Date: Oct 2007 Location: Newmarket, Ontario, Canada Posts: 1,066	Transmission swap - Muncie M21 to New Process MY6 I am wanting to get into an o.d. for my '63 and am thinking of swapping my M21 for an MY6. The ratios for the Muncie are 2.20, 1.64, 1.28, 1.00 The ratios for the New Process are 3.09, 1.76, 1.00, 0.73 The two tranny's are physically identical, as are the input and output shaft sizes and splines so clutch swap and driveshaft work are not needed. Shifter location may be an issue. I am looking for anyones experiences. Maybe someone here has done this swap already. Just looking for any other input. Greg. __________________ 1 Corinthians 10:13 1963 Chevrolet 1/2 ton 2010 Camaro SS/RS 2014 Jeep Grand Cherokee 2016 Jeep Cherokee

09-02-2013, 10:52 PM	#2
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,521	Re: Transmission swap - Muncie M21 to New Process MY6 Pm Keith Seymore. He has a factory installed one in his truck. He could answer your questions. http://67-72chevytrucks.com/vboard/member.php?u=56854

09-02-2013, 11:21 PM	#3
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,246	Re: Transmission swap - Muncie M21 to New Process MY6 I believe there are a couple members on the '60-'66 forum that have installed the MY6. __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE

09-03-2013, 06:56 AM	#4
D13 Registered User Join Date: Feb 2007 Location: Memphis MI Posts: 1,851	Re: Transmission swap - Muncie M21 to New Process MY6 Input shaft retainers on the A833 (which is the trans for MY6) is a different size (except for a very few) which means you will have to have the A833 specific bell housing, and make sure you get the one for the correct style clutch (manual or hydraulic). Also MY6 shifters are unique (your Muncie won't work) and new ones are not available, so be sure you have the right one. They also appear to be different 2wd/4wd but probably either would work. There are a couple threads about them on the board, either here or in 73-87 section. __________________ 1987 2 ton 1982 250/TH350 beater in progress Dad's 1981 3/4 L6 3 on tree posi and no options, awaiting restoration or scrapping Plus a mess o' tractors

09-03-2013, 07:52 AM	#5
jjzepplin Registered User Join Date: Feb 2012 Location: Ruskin Florida Posts: 4,546	Re: Transmission swap - Muncie M21 to New Process MY6 How much for that m21? __________________ 70 swb 4x4 406sbc 700r4 203/205 d60/14blt locker yadda yadda http://67-72chevytrucks.com/vboard/s...88#post6935688 Yeller 72 Blazer 2wd conversion project "No Daggum Money" http://67-72chevytrucks.com/vboard/s...d.php?t=550804 LS1-T56 3.73 LSD super budget build Blanco-2014 Sierra SWB https://67-72chevytrucks.com/vboard/...d.php?t=810350

09-06-2013, 01:53 PM	#7
Greg63 Enjoy your truck Join Date: Oct 2007 Location: Newmarket, Ontario, Canada Posts: 1,066	Re: Transmission swap - Muncie M21 to New Process MY6 Found one! Aluminum case, shifter & linkages, plus shifter handle. Also, the front bearing retainer fits my bellhousing hole. My next project will soon be under way. Greg. __________________ 1 Corinthians 10:13 1963 Chevrolet 1/2 ton 2010 Camaro SS/RS 2014 Jeep Grand Cherokee 2016 Jeep Cherokee

09-11-2013, 06:43 PM	#8
Greg63 Enjoy your truck Join Date: Oct 2007 Location: Newmarket, Ontario, Canada Posts: 1,066	Re: Transmission swap - Muncie M21 to New Process MY6 In and done. Pretty straight forward swap for me. The front bearing retainer fit right into my truck's bellhousing. It may have been turned down, but I didn't have to get it done. I spent most of my time with the MY6's shifter - cleaning out the old grease and removing the shifter handle. I like the way the truck lopes along at 60 mph now. This was a good swap. Greg. __________________ 1 Corinthians 10:13 1963 Chevrolet 1/2 ton 2010 Camaro SS/RS 2014 Jeep Grand Cherokee 2016 Jeep Cherokee



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