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th400 to np241

Discussion in 'The Garage' started by Cole, Jul 25, 2006.

  1. Cole

    Cole Registered Member

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    i have a 1986 k20 silverado with the np208 t-case which needs to be rebuilt...i also have a np241 from a 1989 k5 is it possible to just swap out cases...will i need an adapter if so who makes them...im looking for the cheapest and easiest way to get the silverado up and running so i can get out on the trails.
    Thanks, Cole
     
  2. ryan22re

    ryan22re 1/2 ton status

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    Adapters are the same. Bolts right up.
     
  3. wayne

    wayne 3/4 ton status

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    You need a 32 spline input for your 241 if it came from a K5 with a 700r4 trans and you are putting it behind a th400. As mentioned it will bolt to your existing adapter.
     
  4. tavis

    tavis Registered Member

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    Yes you either have to find a 32 spline input np241 from behind a 4l80e/NV4500 or replace the input shaft on the T-case (GM part#12547998)

    I am assuming that the current setup is TH400->np208. If you currently have the a 700r4->np208 you will have to move the crossmember forward ~1.5" to accomidate the shorter TH400.

    T.
     
  5. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Shouldn't have to move the crossmember at all.
     
  6. Cole

    Cole Registered Member

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    is it possible to swap the input shaft from the 208 to the 241...
     
  7. mikey_d05

    mikey_d05 1 ton status GMOTM Winner

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    I doubt it, but new inputs are easy enough to find. Make sure you get the bearing along with input. When I swapped my input for a 32 spliner the original bearing was too thick.
     
  8. wayne

    wayne 3/4 ton status

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    No.
     
  9. wayne

    wayne 3/4 ton status

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    When I did it I didn't need to swap any bearings. Do you have a part number for the bearing you used compared to the origional?
     
  10. mikey_d05

    mikey_d05 1 ton status GMOTM Winner

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    Nope, but I do know that my case was a passenger drop and the case I got the input from was a driver drop. My case is an '89 but I have no clue what year the other case was.
     
  11. wayne

    wayne 3/4 ton status

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    That might be it. My inputs came from pass drop cases.
     
  12. hack500

    hack500 1/2 ton status

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    another thing to keep in mind is that a 241 has a different overall-length than a 208.
     
  13. jp0863

    jp0863 1/2 ton status Premium Member

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    i did it in mine, all i had to do is swap the input, very easy and it cost me about $30 from jb conversions. i also did the sye on mine too so i needed new driveshafts anyway. if i recall correctly the input is 6 bolts, but very easy to do. slap on some silicon and call it good. dont know much about whether or not the stock drive shafts would work, but they should.
     

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