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swapping out a 700r4 to a th400, 1991 full size GMC jimmy

Discussion in 'The Garage' started by rlanc79, Jan 15, 2006.

  1. rlanc79

    rlanc79 Newbie

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    I have a 1991 full size GMC jimmy with a 5.7L (350) TBI. the 700r4 died after 164k, I know I was lucky to get that out of her. I'am going to install a th400 and t-case and need some head-up info. any help would be greatly appreciated. thanks Rob.:confused:
     
  2. u2slow

    u2slow 1/2 ton status

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    Dunno what the ECM will do when it can't engage the TC lockup. :crazy:

    If you stick with a 241, your driveshaft lengths will not change.

    Since you'd need a fairly rare 90-91 32-spline RH drop NP241... it might be easier/cheaper to swap the input gear. The gear itself is used on any 88-99 NP241/NP243 from a TH400/4L80E/5-spd application.

    Th400/NP241 adapter is the same for the older NP208. 85-90 should work. The 4L80E version may work also (91-99) although I haven't proven it. If you are shopping for a used trans, there's a change the adapter may already be attached. Here's a pic of what you're looking for:
    [​IMG]
     
  3. rlanc79

    rlanc79 Newbie

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    u2slow thanks for the info.
     

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