1977 1978 Rivieras with the 403, did they automatically come with TH 400?

Discussion in 'The "Juice Box"' started by berigan, Jun 9, 2021.

  1. berigan

    berigan Well-Known Member

    I always come up with questions I'm not sure the best part of the forum to put up, but ... it does say above, "Ask all your auto trans and torque converter questions here." ;)
    so did 403's get the TH 400 on Rivs, or all other cars with 403's or not? I've looked all over, window sticker of a Riv online (Just said Automatic transmission)

    Thanks!
     
    Last edited: Jun 9, 2021
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    upload_2021-6-9_13-49-47.png
     

    Attached Files:

  3. BRUCE ROE

    BRUCE ROE Well-Known Member

    I have a 77 Olds 88 built with a 403. It had the heavier brakes, rear axle,
    and wheels associated with a 403. But the trans was a TH350, the TH400
    might have been standard on a 98, but not on the 88. So I would expect
    the the same on a lessor model 77 Buick.

    The car now has a 70 Cad TH400, converted to switch pitch. Bruce Roe
     
    berigan likes this.
  4. berigan

    berigan Well-Known Member

    thanks for the information. Interesting. Bruce, Like you said, it may be the LeSabre got the TH350, whereas the Electra and the Riviera would get the TH400. Perhaps we will hear differently....
     
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Is it possible that the Lesabre got the THM375?
     
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Yes, but the 375 and the 350 look the same except the 375 always has a longer tail shaft. It's beefier inside, but that is not apparent just looking at it compared to a 350 long shaft. It may no longer have been used in 77.
     
  7. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    After a bit of research, there was a THM 375, and a THM 375B. The 375B was a modified 350, and the 375 was a modified 400.

    From the Doug Sessions THM350 book,
    THM375B.jpg
    And from the Doug Sessions THM400 book,

    375.JPG
     
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  8. BRUCE ROE

    BRUCE ROE Well-Known Member

    So, there was an upgraded TH350 and a downgraded TH400, both carrying
    the 375 number. Bruce Roe
     
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Yes, that's what I got from the 2 Ron Sessions books on the 350 and 400. No wonder there is confusion.
     
  10. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    There is mass confusion regarding the th375. I've read a bunch of articles on it and each one is different. Its rare and relatively undesirable which isn't helping.
     
    berigan likes this.
  11. BRUCE ROE

    BRUCE ROE Well-Known Member

    The Cad Seville also came with a TH400 and (Olds) 350. Bruce Roe
     
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  12. nekkidhillbilly

    nekkidhillbilly jeffreyrigged youtube channel owner

    there is also a th350c as well which is the th350 with a electric lockup converter my 83 and my friends 80 both had those. the th375 is long shaft iirc and wouldnt fit under an 77 up b body trans tunnel. its basically a long shaft th350.
     
  13. Mark Demko

    Mark Demko Well-Known Member

    Theres also the T-350 used in the V6 applications that has one LESS clutch per pack.
     
  14. GSX 554

    GSX 554 Gold Level Contributor

    Weren't Those were the years that there was a fire at the Transmission plant and a lot of vehicles got whatever trans that they had available ?
     
    Mark Demko likes this.
  15. Mark Demko

    Mark Demko Well-Known Member

    I got that info from the Buick service manual.
     

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