Hot Rods 3 spd manual, what the he !! am I

Does anybody out there know where I can look up Saginaw 3 spd manual transmissions for what they are? What I'm getting at is I would like to know where to find the trans identifying names and or pictures like (M26/M27) or (M10/M13) or (MC1) or (M62/M64) and even I think (MC318/MC319) and the likes. Just trying to get a better idea of them and if I need parts for them what to give for information to the parts guy/gal.
I hear people talk about RPO codes, I know that is Regular Production Order/Options giving what the Vehicles came equipped with and then I have heard people from other forums say there RPO code for there trans is ****. Just trying to understand these trans better.
Maybe I should say how does one understand these Saginaw trans's for what they are?

Thanks for any help or Links given.

 

Some people give Google a shot...

 

Hemmings article from 2011
it is a start, https://www.hemmings.com/magazine/hmn/2011/05/Saginaw-Four-Speeds/3698661.html

and another article
https://www.advanceadapters.com/tech-vault/4-saginaw-3--4-speeds/

 

Ether one of your two Links did me any good. I am looking for there "letter & number" designations like what I ask for above in my first thread post.
Thanks anyway.

 

Been there done that and came up with empty hands.
Thanks.

 

Anyone else know of a list of these 3 spd's letter number designations.

 

Pictures would help.

 

I don't have all the 3 spd Saginaw's that GM made in picture form!
I'm after information with identification RPO codes or there common industry names and the likes.
How many 3 speed Saginaw's did GM make, maybe that question will get something started. Inquiring minds would like to know. LOL

 

Most guys go on the number of "rings" cut around the input shaft, to see what the first gear ratio is; that will also give you second gear, and as we all know, third is 1:1. Us hot rodders, can't be too worried about part numbers and all, at least not when there's a "simpler" way to I.D. something. So, how many rings does your Sag 3 speed have? NO rings= 2.85, 1.68, 1:1; 1 ring= 3.11, 1.84, 1:1; 2 rings= 3.50, 1.89, 1:1 (that's first, second, third). The 3.11 and 3.50 first gear units are Vega/Monza units, and have "narrower" gears (think strength), and are not as strong.
I am Butch/56sedandelivery.

 

^^^^^ Actually
No Lines (grooves) 2.85 1.68 1.00
1 Line..................... 2.54 1.50 1.00
2 Line..................... 3.11 1.84 1.00
3 Lines.................... 3.50 1.89 1.00

 

I would start at the GM heritage web page, with the Restoration Info packages for Chevy cars/trucks. I don't know if they have what you want, but that is the most likely place I can think of.

good luck

 

On another Forum I got some answers only to get a Saginaw 3 spd Truck trans having 5 mounting holes, the trans is specific to a certain bellhousing # 6263756, 5 hole mounting fitment. Years in use for the bell is 1973-1984 so I guess the/this trans follows them years also. Pic below of bellhousing and trans.

Still looking for my original question 1st post of mine.

 

To answer your original question a little bit...we use the RPO code to talk about the Muncie 4 speed transmissions, such as the M20/M21/M22. But no one I know of talks about the Saginaw transmissions using the RPO code.

Folks do mention the low gear ratio, and do mention the truck 5 bolt mounting pattern, and the truck larger diameter front bearing retainer. If you want to figure out what a transmission is originally from, find the stamped numbers on it. Some of the do***ents I mentioned in my previous post have info about what those numbers mean, and some of the Chevy parts books do, also.

 

The 4 bolt side cover trans are not a Saginaw. They are a Muncie 318 or with overdrive a 319, The Saginaw didn't come out until the mid sixties and its full syncro, and the Saginaw has 7 bolts on the side cover. and number of the rings around the input shaft indicate the gear ratios.

 

I have Googled/Researched all the casting numbers as well with there date codes and really haven't found much. Casting numbers will give you a grouping that uses some individual pieces from trans to trans and then the date codes only tell of the year made not the hole year just the last number like 3 or 4 which could mean 73/74 83/84, so if you don't know the life spam of the trans you are guessing at it. I have a web place to go to for information on different trans info, here it is (mmerlinn.com) this web site uses some RPO codes and as well calls some trans by just Muncie and Saginaw.

 

Googled this using Wiki and found this. I know its fuzzy click it anyway

 

I'm trying to help, but you don't seem to be listening. Did you look for stamped numbers? They are not casting numbers.

Sent from my Trimline

 

^^^^^ Saginaw 3-speed and 4-speed code location. Driver’s side of case below side cover.

 

And stamping in regards to VIN

 

I’m confused [emoji848]. What exactly is the end goal of the original post??? [emoji3]


Sent from my iPhone using The H.A.M.B. mobile app

 

I think he's just trying to figure out what some transmissions came from, so he knows what to order parts for. Which might not be necessary....as there weren't really many changes to these transmissions over the years or for different models.

 

I see. I have a few and have swapped parts before but was wondering about the original question.


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Looking at the casting numbers on the case, tail shaft and side cover will get you close. The VIN stamp thing gets you to an exact car. The VIN stamp was removed from my M20, pointed out to me by the rebuilder I used. But he narrowed it down to it coming out of a '64 Corvette with a 4.11 rear.

 

the stamped numbers shown are not real helpful, but combined with casting numbers to get the year, they could be.

Some transmissions had a partial VIN stamped on them, some didn't. It was common on Corvettes even in the 60s, and other cars/trucks in the 70s and later.

here's a parts book page with a little info on the stamped numbers

 

@squirrel from @MikieOne other post. " S4A19 "

 

Just because a transmission might have been made in a certain location or plant it doesn't matter. A Muncie 318 is still a Muncie trans.

 

The next time you're at a good swap meet and you see that big "Hollander Interchange" that looks like and old monster phone book, buy it. I have 2, 1 from 65-75, one from 50-something to 65. If you look deep enough in that book it might tell you how many times Lenny took a **** on company time! Ok, so it's not really that complete but it was called "the bible" for a reason. I'd take a look for ya within the next couple days but I need something to go by. An empirical search would be quite time consuming and frankly not worth doing.

 

Hi, Im new here, and I know this is an old thread, but one that hasnt been fully explained, so I thought I may be able to shed some light on this transmission. This post may be a bit long, and much of my information is from about 16 hours of internet research, although I do have years exp turning wrenches.

First I want to clear up a misconception I had when growing up. I always thought 'muncie' was a company that made some bad*** transmissions. AFAIK 'muncie' refers to GM's plant in muncie Indiana, while 'Saginaw refers to GM's plant in Saginaw Michigan. Please correct me if I'm wrong. Most people reading probably already know this. I just post this for those that dont, or my own clairification. 'muncie' were generally used for heavy duty, and performance applications, while 'saginaw' were typically light duty, or low horsepower applications. Again please correct me if I'm wrong. Both of these were manufactured by General Motors Corporation.

Now, on to this transmission. Off my property I bought 5 years ago I pulled a 1969 Carry All (Suburban) Panel Van. Someone at sometime had rodded it a little. street mostly, minor mods.

Anyway, it has what I believe to be stock transmission identical to the original posters. Thinking it may be worth some money, I began to ID it. well that has been a REAL chore, but this is what I found. I believe this is a muncie HD (heavy duty), not a saginaw. The side cover has 7 bolt holes, but saginaw has one bolt hole top center, while this trans has two bolt holes top offset center. The side cover also has a bump below the horizontal ridge toward the rear shift linkage, saginaw do not. Funny thing is I have noticed the tail piece looks alot like saginaw.

Most people online distinguish between 'muncie' and 'saginaw' in that 'muncie' has an aluminum case, and saginaw are cast iron. In fact there are several 'muncie' transmissions that have cast iron cases. There is alot of misinformation on the internet. I dont think its intentional, but one must disseminate truth from myth, or partial information.

'Muncie' did in fact make a heavy duty 3 speed transmission from about 69-73 (im guessing at dates) They are called (I think) SM330 HD (351) Again, I'm looking for clarification if anyone has any. And last night I found out why so very little info is around on these. This is an excerpt from a forum post, this forum if im not mistaken, and explains why few people would have heard of these transmissions:

"Beginning about 1969 GM made a heavy duty 3 speed designated as SM330. It has a 7 bolt side cover similar to the Saginaw, but instead of a single bolt at the top center of the cover, it has a bolt on either side of center. This is a very strong 3 speed which was the base trans supplied behind a BB if you didn't order a 4 speed or automatic. In trucks, it may have been an upgrade option with any of the smaller engines, like the earlier Warner T-89."

Well no wonder they are rare! Who the F' didnt want want a 4-speed or an automatic in 69!?! This ****** also features a 5 bolt-to-bell-housing, which distinguishes it from a 'saginaw' transmission. I believe it is designed to go on a General Motors BB 756 bell-housing or similar. I have not seen any small block bell housing with 5 bolt pattern, but mounts to 4 bolt housing fine without the top bolt.

Also if you open the side cover and compare these to a 'muncie', and 'saginaw' they more closely resemble 'muncie' innards.

So here are my GUESSES based on many hours of internet research:

Sometime in the (late?) 60's, GM moved away from Borg-Warner (temporarily) because they couldnt handle the power from certain engines, and used 'muncies' high torque/heavy duty application instead. 4-speeds were HOT, and automatics were beginig to shine due to newer technology; however there were certain situations where a 3-speed was needed/desired, and GM wanted to offer it as an option lest someone buy a different brand just because they wanted a 3-speed trans. Enter the SM330 HD, these were option only I think, in that you actually had to say I want this vehicle, but I want it with a 3-speed manual, and if the application was over **x horsepower, or high torque etc. then this was the factory solution. If it was a low horsepower/torque, you probably would have gotten a 'saginaw' 3-speed. Its no wonder few people have heard of these, or that there is so little information about them.

I am very interested in any information anyone could provide. especially a repair manual! or exploded diagram. I have never rebuilt a manual, but I may make this one my first. I will upload some pics of my trans.

Note: The trans is UPSIDE DOWN in several pics. (My bench is messy, I know *SIGH*)

Disclaimer: I am here to learn, not argue. I could be wrong, and probably am...

 

The 1971 Truck Unit Service Manual calls it a Muncie 3 speed 83mm transmission.

I thought the 5th bolt on top was first used in 1973, but your transmission has a June 1972 (or 1982?) casting date code. Through 1972, trucks used a bellhousing mounted to the crossmember, but starting in 1973 they did away with that crossmember, and used a crossmember under the rear of the transmission, like cars.

 

I know very little about these transmissions, and nothing about the numbers, but I can share three pieces of information that might be helpful.
A friend of mine bought a brand new 67 Chev 2 dr, and intentionally stayed with a fully synchromesh Muncie 3 speed.
In the early 70s, another friend purchased a basic Chevelle that was build in Canada, and was supposed to be exported for fleet use in the Middle East. This transmission was also a full synchromesh HD Muncie 3 spd.
In the early 80s, I machined the front piece of a later model, full syncro 3 spd to fit in the older Chevy bellhousing for use in a stock car. It worked great.
Bob