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Swap a 700R4 for TH 350, transfer case?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 84_Chevy_K10, Aug 10, 2001.

  1. 84_Chevy_K10

    84_Chevy_K10 Banned

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    What's it take to make an NP 208 from a 700R4 application bolt to a TH 350? I am under the understanding that they're the same 'case, but is there a spacer or something required?

    It's not for my truck, it's for my friend's 86 K10 shortbox.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  2. 4x4blazer

    4x4blazer 1/2 ton status

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    I swapped from a 700r4 to a th400. I think the 350 and 400 are the same as far as swapping goes. Anyways, my transfer case bolted right on, I just had to get a different tail shaft. There is a kit you can buy from places like Summit for that swap. Hope this helps.
     
  3. pcorssmit

    pcorssmit 1/2 ton status

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    First, why? Do you not like having OD? Or are you looking to get rid of the lower first gear?

    The bolt pattern and spline count are the same, 4 bolts and 27 splines. The difference is the tailshaft stickout, I think the 700 is longer. So a different tailshaft or a different adapter would be required, and most likely driveshafts.

    The TH400 has a 6 bolt pattern and 32 splines.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  4. 84_Chevy_K10

    84_Chevy_K10 Banned

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    His reason for doing it is that he has 3.08 gears, 33" tires, needs to get rid of his 700 because it's about to take a @#$#, and he doesn't have enough money to change his gears.

    I guess he'll need some kind of adapter, or use the NP 203 that he already has (and get driveshafts).

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  5. pcorssmit

    pcorssmit 1/2 ton status

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    So he wants a tranny with a higher (worse) first gear?

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  6. 90idahoblazer

    90idahoblazer 1/2 ton status

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    Pete
    I take it you like the 700R4....do you have tricks for adjusting the Tv cable
     
  7. 86_Chevy_K10

    86_Chevy_K10 Newbie

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    i am the one swapping the trans and i pull alot of stuff and the 700r4 just can' take the abuse a good old th 350 would i mean i paid 125 for a good th 350 and a np203 case and it would be alot easier to use the stock case instead of locating driveshafts unless you have driveshafts?

    86 K10 SWB, lifted, loud, fast, and 1/2 ton axles
     
  8. CaptCrunch

    CaptCrunch 1/2 ton status

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    Are the trannys the same length? There is a version of the 350 that is the same length as a 700R4, but can't remember what years or application. Different length would require you to change driveshafts so if that is the case why not get rid of the slip yoke and just add the part time kit to the 203 if it is needed? Just my $.02 worth though... That is seriously becoming my plan soon

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://www.geocities.com/milnerlives_2000/blazer.htm>http://www.geocities.com/milnerlives_2000/blazer.htm</a>
     
  9. pcorssmit

    pcorssmit 1/2 ton status

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    Adjust it according to the book, real simple. If you feel the need, you can pull it out a tad more, but too much can hurt the trans. Also, buy only genuine GM cables, a lot of the aftermarket ones are not properly made and can smoke the trans.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  10. pcorssmit

    pcorssmit 1/2 ton status

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    I'd be really suprised if you were able to avoid having to get driveshafts. Also, if you have to change the output shaft, it will cost you, you have to tear down the whole trans to change it, which usually turns into a rebuild. As for the abuse thing, the early 700s were weak, yes, but the newer ones are quite durable. The 700 is based on the 350.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  11. 84_Chevy_K10

    84_Chevy_K10 Banned

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    He has 3.08 gears, guys. I love 700R4s but there's just no way that any motor could pull his truck with 3.08 gears in overdrive. It's just not happening. Not with 33" tires.

    The worst 1st gear doesn't matter. It doesn't have problems taking off. We just need to know what it takes to swap the 700R4 out. We've got a TH 350, a NP 208, and a NP 203 to work with here. What's the best idea?

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     

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