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Old 11-26-2020, 02:07 PM   #1
Bobbysgmc
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muncie conversion

I have a 1970 GMC factory shortbed 2wd 350 turbo automatic, with 2 piece driveshaft.I have all the parts and pieces gathered to convert it over to a Muncie M22.While doing some measurements it has come to be that the Muncie is about 4" shorter than the 350.Any recommendations on what to do about the short driveshaft? Please dont just say take it to a driveshaft shop, unless there is no other option.This truck is my daily driver.
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Old 11-26-2020, 02:33 PM   #2
Grumpy old man
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Re: muncie conversion

Call your local driveshaft shop , go 1 piece shaft .
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Old 11-26-2020, 09:23 PM   #3
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Re: muncie conversion

if you want the shorter trans grumpy has the cheapest method otherwise you need to cut the firewall and floor and move the engine and trans back to fit the drive shaft
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Old 11-27-2020, 12:17 AM   #4
Bobbysgmc
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Re: muncie conversion

Sounds like one piece driveshaft is the way to go.Thanks for the advice.
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Old 11-27-2020, 10:40 AM   #5
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Re: muncie conversion

Gonna be quite tight fitting that shifter slightly under the seat!
Assuming bench seat of course.
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Old 11-27-2020, 11:19 AM   #6
Grumpy old man
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Re: muncie conversion

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Originally Posted by geezer#99 View Post
Gonna be quite tight fitting that shifter slightly under the seat!
Assuming bench seat of course.
This shifter body / handle / install kit is designed just for a Muncie conversion in our trucks to fit .



https://www.holley.com/products/driv...parts/3910002#
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Old 11-27-2020, 11:27 AM   #7
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Re: muncie conversion

install kit

https://www.holley.com/products/driv.../parts/3737834
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Old 11-27-2020, 11:30 AM   #8
geezer#99
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Re: muncie conversion

Have you installed one?
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Old 11-27-2020, 11:43 AM   #9
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Re: muncie conversion

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Originally Posted by geezer#99 View Post
Have you installed one?
The pictures above are of my truck . The shifter comes up thru the floor 10" back from the front cab mount bolts , This is with the V8 engine sitting in the V8 stock position using a stock 67 bell housing . it would be about 3 " back if someone had their V8 mounted in the 6 cylinder mounts . The pictures above were taken at a bit of an angle so it may be a bit deceiving .
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Old 11-27-2020, 12:05 PM   #10
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Re: muncie conversion

So how far from the bench lip is the handle when in 2nd or 4th?
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Old 11-27-2020, 01:01 PM   #11
Grumpy old man
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Re: muncie conversion

I don't have a picture of that . I'm using custom made buckets and a stock console . The shifter mounting plate is off set forward and made to install in the forward holes of the Muncie tailshaft also the shifter itself are made to move it further forward and taller for clearance .

This truck was originally a 67 292/3 speed short bed , Project creep lead it to 350 4 bolt with the M22 and a 3.73 posi with 29" tires 3.5/5" static drop and front disc conversion a rear mounted tank and all stainless lines with a wood bed . I swapped out the 6 manual trans cross member mount for the V8 cross member so the engine/ bell housing would be in the stock V8 position , Since I already had a few 67 bell housings that fit the Muncie 22 input it was a no brainer for a period shop truck build . I've done the math it all works .
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Old 11-28-2020, 08:52 AM   #12
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Quote:
Originally Posted by Grumpy old man View Post
I don't have a picture of that . I'm using custom made buckets and a stock console . The shifter mounting plate is off set forward and made to install in the forward holes of the Muncie tailshaft also the shifter itself are made to move it further forward and taller for clearance .

This truck was originally a 67 292/3 speed short bed , Project creep lead it to 350 4 bolt with the M22 and a 3.73 posi with 29" tires 3.5/5" static drop and front disc conversion a rear mounted tank and all stainless lines with a wood bed . I swapped out the 6 manual trans cross member mount for the V8 cross member so the engine/ bell housing would be in the stock V8 position , Since I already had a few 67 bell housings that fit the Muncie 22 input it was a no brainer for a period shop truck build . I've done the math it all works .

Good info here. I too am in the process of trying to figure out how to convert a 67 Short box 250i 3spd over to a 355i / Muncie combo. One question I have is how different are the bell housings? Would I be able to use the bell housing and support position from the 250i set up?
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Old 11-28-2020, 09:38 AM   #13
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Re: muncie conversion

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Originally Posted by Furno68C20 View Post
Good info here. I too am in the process of trying to figure out how to convert a 67 Short box 250i 3spd over to a 355i / Muncie combo. One question I have is how different are the bell housings? Would I be able to use the bell housing and support position from the 250i set up?
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My setup uses the 67 bell housing BUT , I removed the i6 cross member and installed the V8 manual cross member so I could mount the V8 in the stock position and have the shifter fit , Use the V8 linkage , and make life a whole lot easier down the road . the Muncie has to fit the bell housing input hole (67 does ) 68-72 has a larger hole so you would need to add a spacer to provide support . Muncies are famous for breaking the mount ( ears) off and not designed to be just hanging off the bell housing . So if your not interested in changing stock cross members you may just want to remove the i6 cross member and use an aluminum bell housing and a auto trans rear trans mount along with the V8 engine mounts to bring it all forward and avoid clearance issues with the shifter . there is a lot of good info/parts here https://www.5speeds.com/

you can see the "tight" fit of the Muncie trans into the 67 bell housing by the paint removed when I was mocking up mine .
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Old 11-28-2020, 09:39 AM   #14
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Re: muncie conversion

you can probably find a used 5 speed and make it all fit cheaper with less time than using a Muncie , I wanted this set up because it's close to what the "fast cars" were using back in the 60's early 70's . I'm trying to keep this a 67-72 a period build with No computers /injection systems or custom parts that weren't available back then . you know back when you needed a timing light and a screw driver to change the tune and not a computer or metric tools .
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Old 01-04-2021, 10:53 PM   #15
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Re: muncie conversion

I didn't like the idea of leaving the Muncie hanging off the bell housing , So after talking to 2 different Muncie builders I decided to add the tail shaft trans mount and cross member . I did a little massaging to the cross member to have it sit right . Also I was watching some of the Chip Foose C-28 build videos and noticed he added a tail shaft cross member on it under his 5 speed so he's running engine mounts / bell housing mounts and the tail shaft mount on it . If it's good enough for Foose it's good enough for my truck .

https://www.youtube.com/watch?v=zgtmBmzPKOE
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Old 01-05-2021, 10:20 AM   #16
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Re: muncie conversion

Why a 1 piece and not just have 4"longer tube put to the front of the 2 piece?
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Old 01-05-2021, 11:01 AM   #17
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Re: muncie conversion

This thread may help .

http://67-72chevytrucks.com/vboard/s...d.php?t=609685
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