4 speed granny gear to 4 speed Muncie

[69_shortbox]

Hey all,
I’ve got a 69 c10 swb fleetside with a 4 speed granny gear, I also have a Muncie m21 that is like to put in the truck and I’m wondering if anyone has done this swap and what it involves? As far as I know I just need to shorten the driveshaft? Thanks in advance
Tyler
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[weim55]

A few issues to take into account :

The input retainers will likely be different dimensions, This is the large round hole in the bell housing that centers the transmission. The aftermarket makes a sleeve that will convert the car Muncie four-speed to the larger truck bell housing hole.

Some of the car 4 speed Muncies Will have the Speedometer output on the passenger side which would need a longer cable to reach.

Car transmissions will not have the two lower holes that mount to the bell housing threaded as on the truck transmission. You’ll have to use a nut and bolt arrangement instead.

You will have to fab up A reverse light switch arrangement.

Probably have to make a drive shaft from scratch. Your original driveshaft will have a slip yoke in the shaft itself that won’t work on the car transmission.

The shifter can be a little tricky, but there are several solutions to clear the bench seat. I did the swap myself about 30 years ago and I used a 55-57 Chevrolet car Hurst shifter and it worked out well. That said depending on the transmission there are different mounting arrangements so not all shifters fit the same .

Other than that it’s pretty much a bolt in. One more thing to consider: if the trans you have is a real M21 ( very unlikely as these are very rare ) this will have a 2.20 first gear which would positively suck to drive in that truck, not a deep enough first gear. More likely you have the more common M 20 Which has a more livable 2.52 first gear.

Steve weim55 Colorado

[69_shortbox]

Originally Posted by weim55

A few issues to take into account :

The input retainers will likely be different dimensions, This is the large round hole in the bell housing that centers the transmission. The aftermarket makes a sleeve that will convert the car Muncie four-speed to the larger truck bell housing hole.

Some of the car 4 speed Muncies Will have the Speedometer output on the passenger side which would need a longer cable to reach.

Car transmissions will not have the two lower holes that mount to the bell housing threaded as on the truck transmission. You’ll have to use a nut and bolt arrangement instead.

You will have to fab up A reverse light switch arrangement.

Probably have to make a drive shaft from scratch. Your original driveshaft will have a slip yoke in the shaft itself that won’t work on the car transmission.

The shifter can be a little tricky, but there are several solutions to clear the bench seat. I did the swap myself about 30 years ago and I used a 55-57 Chevrolet car Hurst shifter and it worked out well. That said depending on the transmission there are different mounting arrangements so not all shifters fit the same .

Other than that it’s pretty much a bolt in. One more thing to consider: if the trans you have is a real M21 ( very unlikely as these are very rare ) this will have a 2.20 first gear which would positively suck to drive in that truck, not a deep enough first gear. More likely you have the more common M 20 Which has a more livable 2.52 first gear.

Steve weim55 Colorado

It is a real m21 but I have access to an m20 that I’ll use instead! As for some of the other things, the truck was originally a 3 spee collumn shift but someone has converted it to a granny gear 4 speed. By the looks of it, it wasn’t the best job and I’m not 100% sure what I have for a drive shaft etc. It looks like the drive shaft is only in the transmission by about a half inch which doesn’t seem safe to me, but this gives me hope it may be the original 3 speed shaft which should be compatible with a Muncie?
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[weim55]

The yoke will Be different for the granny 4 speed but the remaining driveshaft could indeed be the original and if that’s the case would work without modification with the proper yoke.

Steve weim55 Colorado

[Grumpy old man]

Here's a good video to watch before you buy a rebuilt Muncie M22 off ebay / Craigslist .


https://www.youtube.com/watch?v=RyOWKW21I0c

[69_shortbox]

Originally Posted by Grumpy old man

Here's a good video to watch before you buy a rebuilt Muncie M22 off ebay / Craigslist .


https://www.youtube.com/watch?v=RyOWKW21I0c

I won’t be buying any muncies! I have 2 that I’ve already had running in cars! No guessing games here
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[Grumpy old man]

Originally Posted by 69_shortbox

I won’t be buying any muncies! I have 2 that I’ve already had running in cars! No guessing games here
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Yes, I read that above , I posted the video for all the other guy's considering using a Muncie 4 speed or upgrading one they bought .

[69_shortbox]

Originally Posted by Grumpy old man

Yes, I read that above , I posted the video for all the other guy's considering using a Muncie 4 speed or upgrading one they bought .

My bad! Great information
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[69_shortbox]

Does anyone happen to know the length of a stock 3speed driveshaft?
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