I got owned. It's not a TH400 . Diff between TH350 vs. TH375

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

4WDKC

Full Access Member
Joined
Jan 27, 2016
Posts
2,366
Reaction score
1,090
Location
Southern Florida
First Name
Kacy
Truck Year
1987
Truck Model
V10
Engine Size
350
I thought the 375 was BOP trans..look I learnt somfin... if the 375 is the mostly the same as the 400 like mentioned above, I would have it upgraded to the 400 and then never wonder if you are overloading it..
 

73c20jim

Full Access Member
Joined
Jun 11, 2018
Posts
2,282
Reaction score
2,924
Location
Tombstone, AZ
First Name
Jim
Truck Year
1973, 1973
Truck Model
C20 2WD Custom Deluxe. C10 2WD Base Model
Engine Size
350 CID 195/260 HP Goodwrench crate, 400 CID 2bbl
After all comments, I will probably use the TH350.

Thanks for the replies.
.:patriot:

:big_banana_Dance:
 

hatzie

Full Access Member
Joined
Dec 6, 2011
Posts
566
Reaction score
452
Location
NH
First Name
David
Truck Year
1976
Truck Model
k20
Engine Size
6.5
My first two cars were a 1973 Pontiac Catalina with a 400 Pontiac and 1973 Bonneville Wagon with a Pontiac 455. Both of them had a TH375. My grandfather towed a travel trailer all over the desert southwest for over 210,000 miles with the Catalina on the original transmission. The Catalina was my first car. I killed that transmission with just over 300,000 miles on the clock and I wasn't easy on that beast. The motor lived on in the Bonnie Wagon after I discovered why you don't rev a 455 into the stratosphere.
My 1976 Delta 88, 1976 Grand Prix, and 1975 Cutlass had TH375 transmissions too. Never had a Chevy with one but supposedly they did exist.

There were at least two TH375 transmissions.
The early TH375 is a Medium duty TH400. It has TH375 cast into the transmission body. This one is a TH400 with one less clutch in each drum and an output shaft with TH350 diameter and splines. It's a pretty stout transmission.
The TH375B is a Heavy duty TH350. This one is still pretty stout but not as stout as the earlier TH375.

If it works and it's the right bellhousing pattern I wouldn't hesitate to use it... Or you could put a 350 Rocket in your truck.
 
Last edited:

78C10BigTen

Full Access Member
Joined
Apr 12, 2017
Posts
15,562
Reaction score
23,952
Location
pennsylvannia
First Name
Ted
Truck Year
1978
Truck Model
C10 BIG TEN
Engine Size
350
Well crap, now you guys are going to make dig out the book and verify if the 375 is in fact a BOP only. Tune in later. 4 am comes too darn early!!!
You aint gotta tell me! I go to bed at 7 to be up at 3
 

Matt69olds

Full Access Member
Joined
Jan 8, 2018
Posts
2,342
Reaction score
3,584
Location
Central Indiana
First Name
Matt
Truck Year
81
Truck Model
GMC 1/2 ton
Engine Size
455 Olds
You must be registered for see images attach
 

Matt69olds

Full Access Member
Joined
Jan 8, 2018
Posts
2,342
Reaction score
3,584
Location
Central Indiana
First Name
Matt
Truck Year
81
Truck Model
GMC 1/2 ton
Engine Size
455 Olds
The 375B is a heavy duty 350 made for Buick. I figured it would have been used in any heavy duty TH350 application. Doesn’t matter, it’s easy enough to machine the direct piston for 5 clutches
 

Rusty Nail

Full Access Member
Joined
Jan 29, 2015
Posts
9,772
Reaction score
9,633
Location
the other side of the internet
First Name
Rusty
Truck Year
1977
Truck Model
C20
Engine Size
350sbc
My first two cars were a 1973 Pontiac Catalina with a 400 Pontiac and 1973 Bonneville Wagon with a Pontiac 455. Both of them had a TH375. My grandfather towed a travel trailer all over the desert southwest for over 210,000 miles with the Catalina on the original transmission. The Catalina was my first car. I killed that transmission with just over 300,000 miles on the clock and I wasn't easy on that beast. The motor lived on in the Bonnie Wagon after I discovered why you don't rev a 455 into the stratosphere.
My 1976 Delta 88, 1976 Grand Prix, and 1975 Cutlass had TH375 transmissions too. Never had a Chevy with one but supposedly they did exist.

There were at least two TH375 transmissions.
The early TH375 is a Medium duty TH400. It has TH375 cast into the transmission body. This one is a TH400 with one less clutch in each drum and an output shaft with TH350 diameter and splines. It's a pretty stout transmission.
The TH375B is a Heavy duty TH350. This one is still pretty stout but not as stout as the earlier TH375.

If it works and it's the right bellhousing pattern I wouldn't hesitate to use it... Or you could put a 350 Rocket in your truck.


My first car was a 1976 Delta 88 Royale. What a fantastic automobile that was! I continue to look for another one 25 years later.
 
Last edited:

73c20jim

Full Access Member
Joined
Jun 11, 2018
Posts
2,282
Reaction score
2,924
Location
Tombstone, AZ
First Name
Jim
Truck Year
1973, 1973
Truck Model
C20 2WD Custom Deluxe. C10 2WD Base Model
Engine Size
350 CID 195/260 HP Goodwrench crate, 400 CID 2bbl
Now I'm back to not being sure which is the better transmission.
 

Boonie

Full Access Member
Joined
Jun 3, 2013
Posts
287
Reaction score
134
Location
El Dorado, KS
First Name
Brent
Truck Year
1974
Truck Model
K25
Engine Size
350
my 74 has a t350, and it hauled hay, fuel, fencing supplies, and pulled a grain trailer for 35 years with no issues.
 

DoubleDingo

Full Access Member
Joined
Jul 3, 2012
Posts
10,098
Reaction score
14,350
Location
Right where I am
First Name
Bagoomba
Truck Year
1981, 1965
Truck Model
81-C20 Silverado Camper Special-TH400-4.10s; 65-C20 with 4:57 gears and Borg Warner Overdrive
Engine Size
Carb'ed Vortec 350; 1972 L48 350
What is BOP?
 
Last edited:

hatzie

Full Access Member
Joined
Dec 6, 2011
Posts
566
Reaction score
452
Location
NH
First Name
David
Truck Year
1976
Truck Model
k20
Engine Size
6.5
My first car was a 1976 Delta 88 Royale. What a fantastic automobile that was! I continue to look for another one 25 years later.

Some of those 70's land yachts and barges like my Bonnie Wagon are nearly extinct. Mom had a 1970 Delta 88 that retired in 1983 with over 380,000 miles. The NYS winter salt ate it up after they moved to Upstate NY.
 

Forum statistics

Threads
42,030
Posts
907,767
Members
33,525
Latest member
Uberbeans
Top