Transmission Identification! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Farnuckel · 09-16-2008, 12:34 PM

I've got a 57 Chevy 3600 with a 235 I6 from a newer vehicle, and a transmission i'm not convinced is original.

It's a 4-speed, with the ratcheting squeeze-brake on the output. On the top of the driver's side, it says GM2 591568. On the passenger side, it says J1955.

I'd like to get a gasket set for this, and I need some parts for the shift handle where it enters the transmission, or a new shift handle. I can't seem to find enough information to know what to get.

Please Help!

Thanks

OrrieG · 09-17-2008, 06:46 PM

The part number you have is for the shift housing, the main case should have another number. The date code is September (J) 19th, 55 or 65, usually there are only three numbers. That tranny was the main stay 4 speed from 47 to early 70's. Early models had 4.6" input bearing retained, later 5.125" retainers. I think the input shafts were different sizes too. I thing the shifters are all the same. Let me quess that the tabs on the cone that hold the shifter in place are broken?? Common problem. You can still probably go to the Chevy dealer and get the gasket set since it is so common. They will take a lot of abuse, I had one in my 59 that was growling when I put it in and growled for 10 years, about 40K miles but never broke.

Farnuckel · 09-25-2008, 01:46 PM

Thanks for getting back to me. What broke is the cylinder that houses the metal tab that moves the gears. The roll pin is WAY worn out too. it's functional, but VERY sloppy, and i fear may brake more. I ended up making the gaskets from a gasket material I had. Hopefully they hold up. Would I put 80/90 Gear Lube in there? or ATF? I was guessing gear lube.

solidaxel · 09-25-2008, 03:42 PM

80-90W should remove the heat,
You could use RTV for gaskets in a pinch if you let it set up a bit, works good on the rear end cover also!

1-ton of fun · 09-25-2008, 04:08 PM

i think those are the sm420 but i may be wrong

Farnuckel · 09-30-2008, 01:07 PM

Looks like it could be a Muncie SM420, from what i'm finding on the internet. Thanks!

sneakysnake · 09-30-2008, 02:59 PM

Here's a pic of several

09-16-2008, 12:34 PM	#1
Farnuckel Farnuckel Join Date: May 2005 Location: Exeland, WI Posts: 163	Transmission Identification! I've got a 57 Chevy 3600 with a 235 I6 from a newer vehicle, and a transmission i'm not convinced is original. It's a 4-speed, with the ratcheting squeeze-brake on the output. On the top of the driver's side, it says GM2 591568. On the passenger side, it says J1955. I'd like to get a gasket set for this, and I need some parts for the shift handle where it enters the transmission, or a new shift handle. I can't seem to find enough information to know what to get. Please Help! Thanks

09-17-2008, 06:46 PM	#2
OrrieG Registered User Join Date: Jun 2006 Location: Idaho Posts: 8,800	Re: Transmission Identification! The part number you have is for the shift housing, the main case should have another number. The date code is September (J) 19th, 55 or 65, usually there are only three numbers. That tranny was the main stay 4 speed from 47 to early 70's. Early models had 4.6" input bearing retained, later 5.125" retainers. I think the input shafts were different sizes too. I thing the shifters are all the same. Let me quess that the tabs on the cone that hold the shifter in place are broken?? Common problem. You can still probably go to the Chevy dealer and get the gasket set since it is so common. They will take a lot of abuse, I had one in my 59 that was growling when I put it in and growled for 10 years, about 40K miles but never broke. Last edited by OrrieG; 09-17-2008 at 06:48 PM.

09-25-2008, 01:46 PM	#3
Farnuckel Farnuckel Join Date: May 2005 Location: Exeland, WI Posts: 163	Re: Transmission Identification! Thanks for getting back to me. What broke is the cylinder that houses the metal tab that moves the gears. The roll pin is WAY worn out too. it's functional, but VERY sloppy, and i fear may brake more. I ended up making the gaskets from a gasket material I had. Hopefully they hold up. Would I put 80/90 Gear Lube in there? or ATF? I was guessing gear lube.

09-25-2008, 03:42 PM	#4
solidaxel Registered User Join Date: Dec 2002 Location: Cactus Patch So. Az Posts: 4,749	Re: Transmission Identification! 80-90W should remove the heat, You could use RTV for gaskets in a pinch if you let it set up a bit, works good on the rear end cover also! __________________ 53 TuTone Extended Cab 350 4-Spd 3:08 (SOLD) 53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25 55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73 62 Solidaxle Corvette Roman Red (327 340hp 4spd 3:36) C4 & C5 suspension tube chassis LS 3 4L70E 65 Corvette Coupe 327 350hp 4spd 4:11 78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42 2000 S-Type 3.0 (wife cruiser) 2003 GMC SCSB 5.3 4L60E 3:42

09-25-2008, 04:08 PM	#5
1-ton of fun polishing a turd Join Date: Dec 2004 Location: houston, tx Posts: 674	Re: Transmission Identification! i think those are the sm420 but i may be wrong __________________ 59 chevy apache 31 4x4 - my project: http://67-72chevytrucks.com/vboard/s....php?p=8668512 53 buick special - straight 8 sled - blow through turbo 47 gmc - flatbed hot rod build 99 ford econoline e350 - 4x4 converted family roadtrip/overlanding rig AKA 'Monstervan' AKA 'Daddy-Van'

09-30-2008, 01:07 PM	#6
Farnuckel Farnuckel Join Date: May 2005 Location: Exeland, WI Posts: 163	Re: Transmission Identification! Looks like it could be a Muncie SM420, from what i'm finding on the internet. Thanks!

09-30-2008, 02:59 PM	#7
sneakysnake It's a catastrophic success. Join Date: Jan 2003 Location: Oklahoma Posts: 2,077	Re: Transmission Identification! Here's a pic of several Attached Images

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