TH400 vs. TH375

[J Knight]

I traded my neighbor a TH350 for a TH400. Currently the TH400 is in the 85 GMC. The 85 GMC was originally equipped with a V6/TH400. After talking to someone I was told it might be a TH375. My neighbor and I are not sure wich one it is but it looks just like a TH400. So my question is, is it a TH400 or a TH375 that were used with a V6s and how can you tell the difference between the two? Also is the TH375 as good as the TH400? I'm going to have it rebuilt to put behind my 454 in my 82 with a stall, shift kit, and manuel valve body.

 

[Brandon_l1000]

hey man should be marked on the bottom of the tailshaft housing. the 375 was a light duty 400 but if you rebuild it you can have 400 parts put in and it will be just as strong as the 400. the difference was they accepted the th350 driveshaft yoke. by the way the 400 and 375 shared the same housing so they look the same. hope that helps.

 

[J Knight]

Ok so if its basicly the tailshaft that is different, can I make it a full TH400 by putting a TH400 tailshaft?

 

[Brandon_l1000]

Ok so if its basicly the tailshaft is different, I can make it a full TH400 by putting a TH400 tailshaft?

no not exactly the internals are lighter duty fewer clutches things like that. the cases are exactly the same but all the internals can be switched for 400. so if you were going to have it rebuilt any way, you can have all the part you were going to put in the 400 put in the 375 and you will have a 400. I have a friend that had one rebuilt and dropped it in a oldsmobile behind a 455 and that thing was bullet proof. the th375's were for full size cars with bigger small blocks.

 

[HotRodPC]

Th375 were only used for about 4 years, like 71-74 something like that. A bit rare. They are Th400's all day long EXCEPT they have the length of the of the Th400 longer shaft but the Output shaft is 27 spline. The exact same as a Th350. In short, it's a Th400 with a Th350 output shaft. I also have not seen one that had less clutches as of yet, but I've only built 2 out of Chevrolet Station Wagons. IIRC, one was a SBC 400 motor, and one was a BBC 400 (402) motor. Kinda like the Caprice or Impala Wagons type vehicles.

And Yes, in Big letters, the Tailshaft housing is Marked THM375. You can't miss it. It's not small at all. Probably at least 1 inch tall letters.

 

[J Knight]

Awesome, Im going to check the tailshaft.

 

[Brandon_l1000]

Th375 were only used for about 4 years, like 71-74 something like that. A bit rare. They are Th400's all day long EXCEPT they have the length of the of the Th400 longer shaft but the Output shaft is 27 spline. The exact same as a Th350. In short, it's a Th400 with a Th350 output shaft. I also have not seen one that had less clutches as of yet, but I've only built 2 out of Chevrolet Station Wagons. IIRC, one was a SBC 400 motor, and one was a BBC 400 (402) motor. Kinda like the Caprice or Impala Wagons type vehicles.

And Yes, in Big letters, the Tailshaft housing is Marked THM375. You can't miss it. It's not small at all. Probably at least 1 inch tall letters.

Yea u could be right on the clutches its been a while since I fooled with one lol

 

[akchevrolet]

Mine is a th375 but but it doesnt say it on the tail shaft housing. took me awhile to get right rear seal for it. and I feel like I eventually will have to build mine or have rebuilt in the near future good to know the eternals are the same

 

[Matt69olds]

Mine is a th375 but but it doesnt say it on the tail shaft housing. took me awhile to get right rear seal for it. and I feel like I eventually will have to build mine or have rebuilt in the near future good to know the eternals are the same

Same seal, same output shaft spline count as a TH350.

 

[akchevrolet]

Yea finally got it figured out. Gonna need to take time off to rebuild it.