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TH400 TECH QUESTIONS...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by KRAZIE87K5, Jul 8, 2001.

  1. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    I know that you can always tell a TH400 by the "TEXAS" shape of its pan. Now the real questions lies inside the TH400...

    Has anyone ever seen different output shafts in TH400 transmissions? I just got home from a parts run to Montreal from Chicago. On the way home HD_DAVE (whom I picked up a very gorgious D60 front) gave me a call concerned about the TH400/NP203 combo that was included in the trade we negotiated.

    He noticed that the output shaft splines on the TH400 were only 28 splines, similar to a TH350. However, the pan is shaped like any other TH400 pan I have ever seen. Has anyone ever seen this? Anyone that has a TH400/NP203, have you ever looked for a spline count on your trans?

    If all else fails, maybe someone knows where I can find reliable info on this on the internet?

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  2. Jason73K5

    Jason73K5 1/2 ton status

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    I don't know right off hand about spline count, but the shaft lengths are different for different transfer cases. The 203 shaft is much shorter than a 241 shaft (learned the hard way). I don't know if there are more than 2 lengths.
     
  3. DaveDave

    DaveDave 1/2 ton status

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    actually the spline count is 27 spline, trans is about 22 in long as 13 bolt on the pan.

    <P ID="edit"><FONT SIZE=-1>Edited by hd_dave on 07/08/01 09:53 AM (server time).</FONT></P>
     
  4. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Yeah, I have seen these 400's with the 27 spline count shafts before.

    Those are simply a conversion kit that was installed to changed the shaft size and spline count to mate a t-case that was originally mated to a TH350. Many aftermarket tranny businesses sell these kits.

    This kit is an option for those who do not want to pay extra for a t-case that will actually fit the 400 turbo's. People who have the 350 and say, 205 t-case, can simply get any th400 and order the conversion kit to change the output shaft size and spline count to fit their current 205 that was mated to the 350.

    The kit shaft is simply a TH400 out put shaft machined down to the TH350 size and spline count. There should be an adaptor bolted on the end of the tranny housing. Since the 400's are a 6-bolt on the tail shaft, the 350's use 4 bolts. There should be an adaptor bolted on the tail housing to convert the 6 to a 4 bolt in order to use the existing 350-equipped t-case.

    Check out TCI, Art Carr, B&M, etc. and other big name tranny shops. These kits are called '4x4 conversion kits'.

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  5. DaveDave

    DaveDave 1/2 ton status

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    thank, you are the man.
     

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