4 speed Muncie with 3 speed bell housing

[350pwr]

Good afternoon all,
I swapped my old 3 on the tree for a 4 speed Muncie, and I kept the 3 speed bell housing. Unfortunately, I noticed a gap between the gearbox and housing. Muncie retainer is 4.125 inches wide, the bell housing is 5.6875 inches wide. Should I insert a spacer I just received from summit, or will the setup be ok?
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[kwmech]

spacer should be used to help center the trans into the back of the crankshaft.

[Grumpy old man]

The 67 3 speed bell housing is the right size to fit the Muncie trans without a spacer , The 68 up need a spacer . Muncies are famous for cracking the mount ears off if not supported right . What shifter are you going to use ? Hurst makes one to fit the 67-72 Chevy trucks . I also added a tail shaft mount , I wasn't happy having the trans just hanging off the bell housing .

[350pwr]

I am running a Hurst shifter, and I also have a tail shaft mount as well. My bell housing has a larger bore than the Muncie, so it must be a 68 and up bell housing.

[Tator]

Advanced Adapters has a ring to fit. Just used one and it fit great.

https://www.advanceadapters.com/5403

*edit, due to not reading*

Yes, you need to support the input bearing retainer, do not rely on the 4 bolts to keep the trans from moving around. That is a good way to bust an ear or case.

[68 C10 Driver]

Interesting post, I am installing a Muncie M20 in my truck as well. I purchased an aluminum bellhousing and will install a transmission mount under the rear of the M20. I installed a Hurst Competition Plus shifter and got the shifter made for the bench seats. I also bought a new reverse lamp switch so the back-up lights work as they should.

It is funny how very few posts there are regarding the use of Muncies in our trucks...I guess everyone is after the 5 and 6 speed trannies or overdrives. My intent is to build something as it would have back in 68/69 with as much period correct items as possible.

Great post, thanks!

[zicc1835]

Originally Posted by 68 C10 Driver

Interesting post, I am installing a Muncie M20 in my truck as well. I purchased an aluminum bellhousing and will install a transmission mount under the rear of the M20. I installed a Hurst Competition Plus shifter and got the shifter made for the bench seats. I also bought a new reverse lamp switch so the back-up lights work as they should.

It is funny how very few posts there are regarding the use of Muncies in our trucks...I guess everyone is after the 5 and 6 speed trannies or overdrives. My intent is to build something as it would have back in 68/69 with as much period correct items as possible.

Great post, thanks!

have that set up im my step side was a in line6 3 on tree 1 wheel peel now date correct truck 327 mild cam m-20 373 posi ( currently under renovations body work paint heads redone roller rockers main
bearings etc.) love the 4 speed
https://studio.youtube.com/video/_r5WjTNNUcc/edit

[HalfBrit]

Hey Grumpy, wasn't aware there were compatibility issues with the Muncie. I've owned my '70 C10 since 1990 (base/307/3spd). Around '95 I swapped the motor and trans. for a 350/M21 combo. I didn't have any fitment issues at that time, with the bell housing. Maybe I got lucky?

[Grumpy old man]

Originally Posted by HalfBrit

Hey Grumpy, wasn't aware there were compatibility issues with the Muncie. I've owned my '70 C10 since 1990 (base/307/3spd). Around '95 I swapped the motor and trans. for a 350/M21 combo. I didn't have any fitment issues at that time, with the bell housing. Maybe I got lucky?

This thread shows how I installed mine .

https://www.67-72chevytrucks.com/vbo...d.php?t=814944

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 .

[tutone]

Great thread. As stated above, there are not enough informational writeups on muncies in this style of truck. After fooling with these transmissions for the last 40 plus years, I have found out a couple of things that may help. Go to fivespeed.com, or at least that's what I think it is.( he has several muncie help videos on youtube), and pick up a set of replacement steel bushings for your shifter. Also, at least every 15xxx miles, drain the lube and refill. I'm collecting all the goodies to put one in my 68 camaro. Final drive question, I'm seeing 3:73s in the rear with a couple of you guys, I have always put 3:08s in the camaros with a warmed up small block. Any advantage to the lower gear in the trucks?

[LagunaGlide]

Glad to have stumbled into this thread. I have been looking at muncie 4 speed for my truck. I think I will retain the current column shifter and come up with a way to activate reverse with. There is something cool about that 3OTT shifting that I plan to retain.

Good to know about the spacer.

[Accelo]

Decades ago I installed a stock 302 ci SBC in a Camaro I had with 308 gears.
I pulled the motor and installed it in a Corvette with 3:73 gears. Nobody would believe it was the same motor as it ran so much better with the lower gears. The 4 speed in the Camaro would do almost 60mph in first!
3:08 gears are fine but use them with a large motor with lots of torque and be happy.

[geezer#99]

A 3.08 gear with a 2.20 first gear isn’t the best combo.
It’s a long ways from the ideal 10 to 1 overall first gear ratio.
3.73 is better.
4.10 better yet.
4.56 the best.
The last two aren’t ideal for all around driving so using a higher first gear like an m20 2.52 gear helps with the 3.73.
Auto gear has a m22z with a taller 2.98 first. Would work with a 3.08 or maybe better a 3.55.

[68 C10 Driver]

Originally Posted by LagunaGlide

There is something cool about that 3OTT shifting that I plan to retain.

Mine originally had the 3OTT as well, would have loved to still have it, but my father-in-law changed it out for a floor shift a few decades ago. I am going to just keep the floor shift; the M20 is for better drivability on the highway (at least in my mind) over the 3 speed.

[CAMAROBOY68SS]

With my 68 C10, I swapped from a SM465 truck 4 speed to a M21 Muncie out of a chevelle. Yeah the 68 and later truck bellhousings have the larger diameter hole for the trust bearing and that needs to be a solid fit as it can damage the 4 speed. I sold my 465 and the bellhousing and swapped to a passenger car bellhousing. You have to change starters as well doing this as I had to go from a bellhousing mounted one to a block mounted one with the correct nose to fit the bellhousing. I also had to add a crossmember at the tail to mount it, since the passenger car bellhousing lacks mounts.

If you plan on running the stock bell housing, use the spacer.


Like 68 C10 Driver, I bought all the backup light stuff for a 68 Chevelle and made it work so my backup lights work correctly.

Then used a 68-72 Chevelle Hurst comp plus shifter with a bench seat handle. Boot/retainer is then also 68-72 Bench seat Chevelle to look like a factory installed piece.

[68 C10 Driver]

Originally Posted by CAMAROBOY68SS

Then used a 68-72 Chevelle Hurst comp plus shifter with a bench seat handle. Boot/retainer is then also 68-72 Bench seat Chevelle to look like a factory installed piece.

CAMAROBOY68SS, I picked up my Competition Plus online, it was rebuilt and is a late 60s/early 70s. I found a set of shift rods for the C10 that worked out great.

The interior of your truck looks fantastic! I know have something to shoot for. Thanks for setting the bar so high!