The Stovebolt Site Forums The Shop Area Driveline Non syncro 4 speed stamping decifer

I looked around but couldn't find any links to decipher info on my 4 speed non syncro transmission. It is a 590474 case with QM58157 stamped in it. The engine (swapped by previous owner) is a 54 235 and this is in a 46 pickup. It is making some odd noises but still drives and want to rebuild a spare to swap out this winter. I have a couple other 590474 cases, one from a 38 (I was told) and one from a 46(supposedly). I have noticed the 2 spares have different input shafts and the tail shafts are different. Not sure what is in my truck as i haven't pulled it out yet. The truck is still a torque tube style and i would like to keep it that way. Can someone either send me a link or tell me how to tell what i have for transmissions? Thanks...

rock331, The same case "590474" is listed as used in all 4 speed applications for 1931-47 trucks (except LT) as noted in the screenshot below. Same case but different other parts depending on the year built. A check of the GM Heritage site files shows the "QM" serial number designation used on 1947 3100 and 3600 trucks as the RPO 4 speed transmission (built in Toledo).

If you want to confirm the other two transmissions you have, post those serial numbers so we can try and help confirm what they are.

Thank you for the information. The other 2 are TC and PG. I want to rebuild one to swap in but not sure about the input shaft difference from what i see and also i need to use the proper rear bearing retainer and yoke. the PG has a open ujoint and different rear bearing support and the TC doesn't have a rear spline at all (wasn't on it when i bought it) but does have the torque tube rear bearing support. I do have a rear bearing support for a 1940 but the torque tube cover joint looks a little different. The GM heritage site was a great link by the way...

I guess i am just trying to use what i have in good parts, so the replacement goes as trouble free and economical as possible.

Here's what I found in the GM Heritage site files for your other transmissions:

TC = Toledo plant - 1938 - 1-1/2ton Truck (long and short wheel base) & School Bus Chassis

PG = Saginaw plant - 1946 - 1-1/2ton Model 4502 (Chassis w/flat face cowl) & 2ton Model 6702 (Chassis w/flat face cowl) - RPO 348

Differences between the two transmission parts can be found searching through the period applicable Chevrolet Master Parts books.

Just to keep things closer to the existing 1946 truck you have, I would suggest using the PG transmission as your starting point. There are frequently 4 speed "crash box" transmissions being offered in various place on line that you may find good donor parts. There are even occasionally NOS/NORS parts that are offered. You just need to gather the parts info from the Master Parts books to get your search going.

If needed, I can offer some help on exploded diagram parts pics and part number information as I have books that cover that data. Just lets me know and will see what I can help with.

BTW - Post some pictures of the transmissions showing what parts you're currently missing so we can offer further help.

You are good. I tried looking in the GM Heritage site but couldn't find that info. I have been trying to look up different parts on the Master Parts Catalog online but the script is kind of fuzzy. I guess i should try to find a book and buy it.
Great info. I kind of was thinking of using the PG but the rear bearing retainer is for a open driveshaft. I bought a rear bearing retainer from a 1940 which is a little different and was planning on modifying it if i had to but it looks like the TC rear bearing retainer one will work on the PG case. My biggest concern is the input shaft differences. I would hate to rebuild one and then find out i had the wrong input shaft. I might just have to pull the one that is in the truck out and rebuild that. I was just trying to save some down time for the truck but with winter coming i guess it won't matter.
Which would be the best Master Parts book to look for my truck in your opinion?
And thanks again for the help and knowledge...

There's a 1929-1954 Master Parts Catalog on ebay for $65

Here's a CD with the FSM, Master Parts Book, Accessories Manual, and Assembly Manual for $50

https://www.faxonautoliterature.com...air-Shop-ManualParts-BookAssembly-Manual

rock331, You are most welcome on the help and sharing of knowledge (aka = Bolters helping Bolters). Just something that I very much enjoy doing and it helps me learn more as I do the research too.


There are all kinds of Master Parts Books listed for sale in online ads. Some are originals, some are reproductions. I have several different ones, but by no means all of them available. If I had to pick which of the ones I have as a favorite for covering your 1946 truck, I would go with the 1929-53 version. That's knowing that you have access to a 1929-54 and 1929-57 version at the Chevrolet Old Car Manual Project site for those later versions to look up for updated part number details as they do change from year to year.

Yes original paper copies can be had and are so much better to read than the often fuzzy on line copies or some reproductions. Definitely worth the investment IMHO!

Thanks guys. I guess i will buy the printed version. I am old school and like paper in hand. Guess it is from my old auto parts sales days with the rows of books...

I agree with you. I hate stuff on CD. I need to flip through it in front of me in the garage.