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NP203 take apart and Doubler questions

Discussion in 'The Garage' started by oldiron72, Feb 22, 2005.

  1. oldiron72

    oldiron72 Newbie

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    Location:
    Clinton, Utah 84015
    I have an NP203 27 spline count off of a TH350, (I hope, well I'm pretty sure that it is). I'm trying to take it apart and I am having trouble doing so. I want to build a doubler for my '72 Chev 4X4 TH350 w/350 motor w/NP205. I've unbolted the helical gear case from the chain case and it is almost coming apart except a bar or maybe it is a linkage bar that goes from one helical gear part of the case to the other part of the case (chain drive part of the case). It is an internal bar connecting the two halves. :confused: My questions is how do I get the NP203 case to completely seperate? Anyone out there know how to take an NP203 apart so I can begin to build my doubler?
     
  2. az-k5

    az-k5 1/2 ton status

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    There are 3 pieces to the 203. The range box, chain case, and tail housing. You have to remove each seperately. Get all of the bolts out of the tail housing (the yoke doesn't matter). Pull it off, there is a flange fit so it might take some tugging/tapping. Then you can see that rod inside the chain case, there is a pin you need to remove so the bar will fall out. Unbolt the chain case and pull. There will be about 5 dozen needle bearings falling out. Don't worry. You need about 10 of the larger bearings (1/2"long and as big around as a cheap bic pen). That wil get it apart and ready for double assembly. You can change the seals and bearing in the range box if you want.
     
  3. NorthWestFab

    NorthWestFab 1/2 ton status

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    Location:
    Canada Eh.
    When you get your tailhousing tapped off, drive this roll pin thru the shift fork:



    [​IMG]

    Then wiggle the shift fork off. This is what the rod is that is connecting your range box to your chaincase.
     
  4. sweetk30

    sweetk30 professional hooker Premium Member

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    dont for get the product review section there is a sweet list of steps and lots of pics.
     

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