What Trans is this ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

john68c10 · 02-13-2023, 11:40 AM

I'm not up on my transmission identifications. What is this tranny that's bolted to this 454 ?

**LockDoc** · 02-13-2023, 12:01 PM

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Auto transmission id:

LockDoc

60case · 02-13-2023, 12:02 PM

Thm 400

60case · 02-13-2023, 12:03 PM

Looks like a THM 400

**Warrens69GMC** · 02-13-2023, 12:35 PM

Thm400 with bolt on yoke.

**Accelo** · 02-13-2023, 01:01 PM

Yup, the board nailed it.
These were typically used on 1T trucks and motor homes. The bolt on yolks style had the slip joint in the driveline. I included a picture of the output shaft and parts below.
There are at least 4 different style yolks and many require a different style and matching output shafts. They very on how they seal. Some yolks are vented some are not. Some have an "O" ring on the output shaft. A lot of mistakes are made in the interchange. If not done correctly you end up with a leaking output.

To complicate things there is a 375 transmission which is a THM 400 with a 350 style output shaft.
Cheers

02-13-2023, 11:40 AM	#1
john68c10 Registered User Join Date: Sep 2007 Location: Cookeville, TN Posts: 53	What Trans is this ? I'm not up on my transmission identifications. What is this tranny that's bolted to this 454 ?

02-13-2023, 12:01 PM	#2
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,769	Re: What Trans is this ? - Auto transmission id: LockDoc Attached Images __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 -

02-13-2023, 12:02 PM	#3
60case Registered User Join Date: Feb 2015 Location: friendship WI Posts: 174	Re: What Trans is this ? Thm 400

02-13-2023, 12:03 PM	#4
60case Registered User Join Date: Feb 2015 Location: friendship WI Posts: 174	Re: What Trans is this ? Looks like a THM 400

02-13-2023, 12:35 PM	#5
Warrens69GMC Registered User Join Date: Jan 2003 Location: Safford,AZ Posts: 3,621	Re: What Trans is this ? Thm400 with bolt on yoke. __________________ 1969 307, t350 1950 Chevy Wagon 1978 Big 10 1967 C10, 250,3-OTT Last edited by Warrens69GMC; 02-13-2023 at 09:57 PM. Reason: speeling

02-13-2023, 01:01 PM	#6
Accelo Senior Member Join Date: Mar 2015 Location: washington Posts: 2,295	Re: What Trans is this ? Yup, the board nailed it. These were typically used on 1T trucks and motor homes. The bolt on yolks style had the slip joint in the driveline. I included a picture of the output shaft and parts below. There are at least 4 different style yolks and many require a different style and matching output shafts. They very on how they seal. Some yolks are vented some are not. Some have an "O" ring on the output shaft. A lot of mistakes are made in the interchange. If not done correctly you end up with a leaking output. To complicate things there is a 375 transmission which is a THM 400 with a 350 style output shaft. Cheers Attached Images Last edited by Accelo; 02-13-2023 at 01:25 PM.



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