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700R/NP208 to TH400/NP205?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BillyBob, Dec 22, 2000.

  1. BillyBob

    BillyBob 1/2 ton status

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    I'm thinking about getting a non OD tranny because I can slap an NP205 on the end. I'd love to keep my 700R4, but no one makes an adaptor to put the NP205 on it. Is it worth swapping for this reason? Also, what do I need to do in order to swap these? Will it effect my 87's ECU?

    [​IMG]

    <A target="_blank" HREF=http://billybob.coloradok5.com>http://billybob.coloradok5.com</A>
    It's all fun 'n games, till someone gets stuck.
     
  2. 1Blazin71

    1Blazin71 1/2 ton status

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    Advance Adapters makes a short output shaft for the 700R that will allow it to mate to the 205.

    I replaced a T350 with a 700R in my 71 with my original 205. The cross member had to move back about an inch but with the slip yokes, neither driveshaft had to be changed. We did have to bend the t-case shift lever a bit to get it through the stock body location without trimming.

    The angle on the rear might not be optimal, but I plan to go to a 6 lug 1-ton axle soon, so I'll get it dialed in then with a new 1350 driveshaft.

    Advance Adapters is at http://www.advanceadapters.com/.

    I opted for a 700R with lockup and have a B&M lockup controller which allows you to set the MPH at which lockup occurs. Works pretty well but lugs a bit with my 3.73 gears...4.56s are coming soon.

    Good luck.

    Matthew Meyer
    matthewm@inhollywood.com
    '71 K5 - 4" Lift 35"s
    ZZ4 350 - 700R
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Yep, Advance Adapters makes the parts you need.

    If you decide to go with the Turbo 400 anyway, you'll need to get a kickdown switch to make it go into passing gear. It mounts to the accellerator pedal bracket. The old, full-size Jeep Wagoneers and Cherokees came with Turbo 400's and are an easy place to find the switch.

    You'll also need to provide manifold vacuum to the modulator on the right side of the tranny in order for it to upshift properly. Without that vacuum line it will be in 3rd gear by the time you hit 20 mph, even at wide open throttle.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     

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