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TH400/NP205 Adaptor (PLEASE READ)

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by KRAZIE87K5, Jul 16, 2001.

  1. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Take a look at the pics below... I am assuming my adaptor is not complete, because the crossmember I have does not even come close to meeting the adaptor! Here is what I have in the truck...

    Adaptor Close up:http://24.10.209.54/images/86truck/trans/missingmount1.jpg

    Cross member:http://24.10.209.54/bigolk5.htm [​IMG]
     
  2. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    BTW... The adaptor is 6 bolts on both sides... 32 spline output on the TH400.

    Does anyone else smell BFGs burning???
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s
    <a target="_blank" href=http://24.10.209.54/bigolk5.htm>http://24.10.209.54/bigolk5.htm</a> [​IMG]
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Is this a new swap from a Turbo 350 setup? I had to drill new holes for the crossmember when I installed my Turbo 400/NP205 combo.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  4. 502Burban

    502Burban 1/2 ton status

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    Since your K5 didn't come with a big-block, TH400/NP205 combo, you will have to re-drill the crossmember mounting holes in the frame. The new combo is longer, overall, than the stock combo. Also, you will need the transfer case/transmission mounts that go between the adapter and the crossmember. I like the urethane ones from Energy Suspension, part number 3-1106, but of course you can always run some stock replacements. Those two issues should fix your problem.

    Good luck. [​IMG]

    Robb
    '73 GMC Suburban - 502DFI
    <a target="_blank" href=http://community.webshots.com/user/robbrj>community.webshots.com/user/robbrj</a>
     
  5. elkboy

    elkboy 1/2 ton status

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    look at the install pic, it's a 350/205, but it should be close to yours.
    <a target="_blank" href=http://y42.photos.yahoo.com/bc/nepatten/lst?.dir=/Project+K5&.view=t>http://y42.photos.yahoo.com/bc/nepatten/lst?.dir=/Project+K5&.view=t</a>

    <font color=red> Elkboy </font color=red> 82 K5 fuel injected H.O.305, TH350/205, 14bolt/10bolt and 39.5 TSL's.
     
  6. Donovan

    Donovan 1/2 ton status

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    I think that you are missing the correct crossmember. I have a 78 TH400 hooked to a 205 and it does not look like that. I also have a 86 1 ton truck and it has a 6 bolt adapter just like that but it has a 4 speed in front of it. The crossmember is a w-shape instead of a u-like shape. What I mean is the center of the crossmember comes up about 2-3". I doesn't look like the 79 and earlier crossmember. I hope that helps some.

    Donovan
    Bigger is Better
     
  7. Jason73K5

    Jason73K5 1/2 ton status

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    Your crossmember should work fine. I just swapped a th400/203 combo into my '73 which has essentially the same adapter mount as your combo. I also have the same crossmember as you. All I did was bolted the crossmember to the adapter and then jacked everything up untill the crossmember was mating the frame. Then I just drilled new holes and bolted it up.
     
  8. thatK30guy

    thatK30guy 1 ton status Premium Member

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    From the looks of that adaptor, that is an '85 to '91 K30 np205. To run a crossmember under that adaptor, you need to find the 'double hump' member from an '85 or '86, or, from an '87 to '91. I sold an '86 crossmember last week. I have an '87 crossmember sitting on my shed floor. It is all you need to make the thing work. You would also need the rubber mount that sits between the member and bottom of the adaptor. I do not have one. You can get these from GM too. I can sell you the '87 crossmember for $40.00 and you pay shipping.

    Anybody planning on checking out my homepage, forget it, I am still working on it!!!
     
  9. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    I'll take it! Please call me at 630.373.0190 ASAP!

    Thanks a bunch!

    Does anyone else smell BFGs burning???
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s
    <a target="_blank" href=http://24.10.209.54/bigolk5.htm>http://24.10.209.54/bigolk5.htm</a> [​IMG]
     

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