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Th400 for doubler?

Discussion in 'OffRoad Design' started by mudddog91, May 30, 2002.

  1. mudddog91

    mudddog91 1/2 ton status

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    Ive got a friend thats selling a 2 wheel drive 3/4 ton truck thats got a th400 in it.........Ive been told that a 2wd version will work in a 4wd application and How can I tell if its the right one if it can be used?The guy only wants 100.00 for the tranny so thats why im asking!!!!!!!!!!!
     
  2. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Shaft stickout will be around 4 1/2" in order to run the '84 and older NP205 t-cases with 32 spline count. /forums/images/icons/wink.gif
     
  3. 45acp

    45acp 1/2 ton status

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    I may be wrong, I often am but on my doubler setup (ORD) I am using a 2wd TH400 to a NP203/NP205 and I had to replace the main output shaft in the TH400 to one that had 1.375" stickout length and 32 spline count. I'm sure there are different ways to do it.
     
  4. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    I'd look for a 4wd trans personally, they're built in a heavier case. for $100 it might be worth it for the parts, but I'd look for the 4wd case to actually use. 45acp's is a BOP TH400 that never was in a 4wd, he didn't have much choice.
     
  5. mudddog91

    mudddog91 1/2 ton status

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    OK well I bought the 2wd th400 for 25.00 and Id like to use it but its the round style output not the foot style so what year 205 am i looking for and It has the 4.5 inch output shaft so will it work for the doubler or not? Ive currently got a 2wd th400,700r4,th350,and an sm 465 and a 205 for it and also a 203 for the th350.I want to run a doubler but need advice on which setup to use.I run mostly rocks with 39.5's or 42's with 4.56 gears.helpplease! /forums/images/icons/shocked.gif
     
  6. or2play

    or2play 1/2 ton status

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    There is a intermediate housing that goes between the turbo 400 and the np205. That's why the bolt patterns are different. If you are going to build a doubler, you don't need the housing, the 203 rangebox w/doubler adapter bolt right up to the foot shapped bolt pattern on the 205.
     
  7. mudddog91

    mudddog91 1/2 ton status

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    Well i appreciate the help but i dont think you understand what my problem really is.I know about the adapter between the 400 and a np 205 or 203 but they are all the 4 bolt(tranny side) to foot style(transfer side). My transmission has a 6 bolt round pattern with a output shaft thats about 4.5 inches long.Which np203 and which np205 do i need and which factory adapters if any do i need?ALSO WHich setup should i go with? Th400,TH350,700r4,sm465,ive got one of each so............I also have an np203 from a th350 and a 205 from an sm465............Thanks again for all your help
     
  8. or2play

    or2play 1/2 ton status

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    Okay, I see your problem. First off, as to what version 205 to use for the doubler, there is only one choice. You need a 205 that came with a Turbo 400 tranny ( Unless you use a non-GM 205). They are getting harder to find and are a bit expensive. You can convert your 350 or 465 version 205 to a 400 version if you so desire. ORD has the parts to do it. It will need to be completly disassembled and the case itself will have to be machined.
    As for which tranny and 203 to use, here you have some choices. You can use pretty much any GM tranny you want. But you have to have the 203 case that was designed for that tranny. As to what tranny to use, thats totally up to you. Myself for example. I have a 350/203 right now. I'm planning on changing to a 700r4 and a 250 w/doubler. I'm gonna use the same 203. In order to do it I have to either change the ouput shaft in the 700r4 to make it look like a 350, or get a adapter to go between the two. In your case if you decide to use the 400, your gonna need to find a 203 and the adapter that orignally came off of a turbo 400. Keep in mind that there are 3 different length output shafts for the 4wd 400s and 3 different length shafts for the 2wd 400s. So if you got a 400 thats from a 2wd, your probably gonna run into a problem there. I hope this helps you some. If you have anyother questions I'll do my best to help.
     
  9. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    or2play has it mostly right, check the doubler info page on the ord site, there's a long section on what it takes to mate a 203 to the various transmission configurations. You can most likely use your transmission configuration but it may not be optimum for your truck. Read through and see if that helps.
     

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