Are there any documented 69 z's with m-20 and a 3.07 3.31 or 3.55 rear out there? Just curious.

Yes I Have A Gm Of Canada Car M20 373 They Are Out There With 355 And 323

I have GM docs of an M-20 Z/28 with 3:31 gears.

Anybody out there with one with a 3.07 rear gear??

I've only seen one possible one, but I think the axle was changed. A 3.07 would be about undriveable.

The M-20 option is a Muncie OR a Saginaw 4-speed tranny.

The M-20 option is a Muncie OR a Saginaw 4-speed tranny.
The thread started as a Z/28 subject. No Saginaws in Zs.:beers:

The thread started as a Z/28 subject. No Saginaws in Zs.:beers:

Do we know that for sure? I believe the CRG states that the M-20 is either a Munice or Saginaw, I sort of assume it may have been whatever was available. I am not sure there is much difference other than the Saginaw has a cast iron case. They both have the small output, right?

Do we know that for sure? I believe the CRG states that the M-20 is either a Munice or Saginaw, I sort of assume it may have been whatever was available. I am not sure there is much difference other than the Saginaw has a cast iron case. They both have the small output, right?

I's in a footnote.

http://www.camaros.org/trans.shtml#TrannyTrivia

All 67-9 Z's received Muncie 4 speeds.

M20 is GMs option code for a 4 speed manual transmission, so as far as GM is concerned any 4 speed is an M20, it dosen't reflect the transmissions make or model. 4 speed saginaws are M20s, as are all the Muncies as far as GM is concerned. Just so happens Muncie assigned theirs model numbers M20, M21 and M22.

M20 is GMs option code for a 4 speed manual transmission, so as far as GM is concerned any 4 speed is an M20, it dosen't reflect the transmissions make or model. 4 speed saginaws are M20s, as are all the Muncies as far as GM is concerned. Just so happens Muncie assigned theirs model numbers M20, M21 and M22.

So you are in fact saying a Saginaw M-20 may be in a Z-28. I would agree.

So you are in fact saying a Saginaw M-20 may be in a Z-28. I would agree.


:noway: No. Z/28s came with a Muncie only. No Saginaws

:noway: No. Z/28s came with a Muncie only. No Saginaws

Can you verify this? Is the Muncie M-20 better than the Saginaw M-20? I think it may be a wives tale...............

All 67-9 Z's received Muncie 4 speeds.

Can you verify this? Is the Muncie M-20 better than the Saginaw M-20? I think it may be a wives tale...............

Kurt is part of the CRG that is documenting the history of first generation Camaros. What he said is a fact. The Muncie M series saw duty in the highest HP motors GM made. They were the higher torque manual transmission.:thumbsup:

One 6500 rpm shift would destroy a Saginaw trans.

Can you verify this? Is the Muncie M-20 better than the Saginaw M-20? I think it may be a wives tale...............

It's verified. Look in the M20 section in your Assembly Manual - trans part numbers and illustrations show only Muncies with 302/350/396 engines, and show only Saginaws for everything else. No mystery here - it's common knowledge. :thumbsup:

One 6500 rpm shift would destroy a Saginaw trans.

:thumbsup:What he said!:D and that there rules out a saginaw in any 1st gen Z/28, period.

I've only seen one possible one, but I think the axle was changed. A 3.07 would be about undriveable.

Almost!:D My '69 Z had the rear axle swapped out decades ago to a BL coded 12 bolt so I've lived it! When I rebuilt the motor in '85 I thought it would be cool to put the 140 off road cam in there with the stock intake/carb (I was young and stupid). Now combine the 140 cam with the 3.07 gearing and any hill becomes a challenge. I lived with that combo until 1998 - didn't know any better.

I just thought maybe there were some racers back in the day that were looking for a high top end speed and could have ordered the wide ratio muncie and the 3.07 axle for a high top speed. You ought to be able to get it off the line with the low first gear . But it might not be great. There are some L88 69 vettes with factory 3.08 gear.

I had one in high school, 'course I can't prove or document it now though. It was a hard to get moving but had a pretty impressive top end.

Was Dover White with white houndstooth interior, would kill to find that car today. Sold it to a guy in Boulder, Colorado. For $1700.

One 6500 rpm shift would destroy a Saginaw trans.


You really think so? I can't imagine the internals wpuld be much different than the Muncie.

I've seen guys crack and bust the saginaw case without much problem in a high horsepower car. The muncies seem to hold up much better.

You really think so? I can't imagine the internals wpuld be much different than the Muncie.


The internals are MUCH different. Paul @ 5speeds.com just published a manual transmission book, and there are pictures of Muncie and Saginaw internals side-by-side in the book. The Muncie looks much more "heavy duty".

The saginaw was not a performance trans... PERIOD...
GM used Borg Warner T10's before the muncie... Cause they were strong as well...

My first Z that I owned in 69 had a Muncie and 355 gears. I swapped them out fast for 410s. I had a second one that came with 410 and the third was a 373. All but one was a documented Canadian car.