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2wd th400 2 4x4?

Discussion in 'The Garage' started by sams78chevy, Sep 16, 2005.

  1. sams78chevy

    sams78chevy Registered Member

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    I am going to buy a th400 on friday for 75 bucks the only thing is that the guy is into hotrods so it is a 2wd, but cant you just get a shorter shaft and a different tail housing? What all do I need to get to do it? Thanks for the help.
    Also what flywheel was more common on a 78 chevy 3/4t sm465? And also what all do I need to swap a sm465 for a th400? will my front driveshaft work? Thanks

    38.5 inch ground hawgs on brandnew 15x10 white spoke eightlugs for sale. $200.
     
  2. sled_dog

    sled_dog 1 ton status

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    you have to almost 100% disable the transmission and put it back together. I just did this to a TH350. I rebuilt it while I was in there because I took everything out anyway.
     
  3. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    The answer to your question depends on what tailshaft the TH400 has and also what t-case you intend to use. Keep in mind your existing t-case (presumably the one on your 4spd) will have the wrong input shaft and you still need an adapter.

    If you have a 32 spline input t-case and the correct adapter, some TH400's have the correct tailshaft - for these all you have to do is remove the yoke and tail cone.
     
  4. HarryH3

    HarryH3 1 ton status Author

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    I don't know for sure if the process is exactly the same, but I'm guessing that it's similar... I just had the output shaft swapped in a 700R4 this week. We had both transmissions taken apart and the shafts swapped in less than an hour. The entire assembly that holds all of the clutches pulls right out once the pump is removed. I was amazed at how easy it is.

    Once you pull out the "can" that houses all the clutches, there's a single snap ring that you remove from the output shaft. Make certain that you're holding the shaft when you remove the ring, because it's gonna drop right out! :cool1:

    For 4WD apps there is no tail housing. The t-case adapter bolts directly onto the trans instead of a tail housing.

    Your next problem is that I'm pretty sure that your '78 NP-465 has a 10-spline output shaft. Meanwhile, the Turbo 400 has a 32-spline output shaft. :doah: So your transfer case won't fit the Turbo 400. Your best bet is to find a transfer case (and it's adapter) that is already setup for a Turbo 400. The folks at www.advanceadapters.com may have the parts to make your Turbo 400 adapt to the 10-spline t-case, but if they do you can expect to spend $300+ for it. :(

    You'll also need to remove the flywheel and install a flex plate so you can bolt up the torque converter.
     
  5. Keith in CO

    Keith in CO Registered Member

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    Th400

    There are three lengths of tail shafts for the TH400, ranging from 4"
    to 13". I have both a 2WD and 4WD TH400 which have the 4" shaft. The 4WD tail shaft housing also has a flange to bolt the t-case to. If you have to change the shaft, you have to take it out through the front of the transmission (taking it all apart), but if the 2WD trans you are looking at has a 4" shaft, you may (I am not sure) be able to swap tail shaft housings from the rear without disassembling the transmission. Beware too that TH400s can have either a Chevy or BOP bell housing bolt pattern, although Summit has adaptors to go either way for about $50.
     
  6. divorced

    divorced 3/4 ton status

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    :shame: :shame: :shame:




    .
     
  7. sams78chevy

    sams78chevy Registered Member

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    so do you guys think i would be better off buying a th350 with a np205 for 100bucks, The tranny got water in it but i think if i do a rebuild it will fix that?
     

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