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NP 203 Doubler ?s, need some answers

Discussion in 'The Garage' started by tlspeed, Mar 27, 2006.

  1. tlspeed

    tlspeed Registered Member

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    I need a question answered about the np203 t-case, wondering if you guys could offer some assistance. First, I would like to build a doubler using a np203 and np205. My current transmission and t-case combo is a th350, and np203. What I would liked to do is build a doubler without taking my truck out of commision for very long.

    My Question: I have np435 manual (i believe) and np203 combo sitting around (from and old 3/4 ton dodge). I know the inputs and adapter bolt patterns are different from the np435 to the th350. What I would like to know is if the shaft and the bolt patterns on the back of the range box part of the np203 off the np435 are the same as the shaft and bolt patterns on the back of the range box part of the np203 off of my th350.

    Ideally what I am asking is can I take the np203 from the np435, split the chain case off of it and use the range box, build the adapter and have a shaft made to suit my needs. Then once done, unbolt the np203 off of my th350, split it, remove the chain case, and bolt my adapter and shaft to the range box part of the np203 then bolt on the np205. Then build my crossmembers and what not.

    Any info would be appreciated. Thanks guys -Troy-
     
  2. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    wait... why mess with the dodge junk again? The process of removing the 203 range case from the rest of a 203, putting the intermediate shaft in there and bolting it to the adapter is like a 1 hour job. 2 if you are swilling beer and/or taking your time. Not 100% sure why its worth the effort to mess with 2 different 203s, tranys etc. That just gives me a headache. lol.

    j
     
  3. tlspeed

    tlspeed Registered Member

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    I dont want use any part of the dodge tranny and 203 except the range box shaft IF its the same. What i want to do is just build the doubler using the range box from the dodge 203 as a template or mock up, then swap the adapter and 205 to my existing 203 range box on my th350 in my truck. hope that clears up things. Keep in mind i want to do this in order to have the least amount of down time on my truck, and if im building my own double the truck could be apart for a little while
     
  4. dremu

    dremu Officious Thread Derailer Premium Member

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    Uhh ... I think what you're saying is you want to build the doubler adapter and the intermediate shaft yourself, and you want to use the Dodge '203 as a template for your GM '203.

    It would be easier and quicker, if not cheaper, to buy a premade doubler adapter and shaft from e.g. ORD, NWF, etc.

    You could do as I did and collect Chevy '203's for a while, and then build the Doubler as you have time and money, sitting next to the truck. Chevy '203's are a dime a dozen (if rather heavy!)

    Doesn't directly answer your question... I don't know if the Dodge '203's range box is identical to the GM, which is what you need to know if you're gonna DIY. If you are, though, I think you'd be in for MORE downtime than if you bought off-the-shelf.

    -- A
     
  5. tlspeed

    tlspeed Registered Member

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    I am a DIY guy, mainly because it costs to damn much for a college kid like me to afford an off the shelf doubler. Plus, I have access to enough tools, resources (buddy works in machine shop), and knowledge to build one. Basically I am just asking if there is a difference between the dodge and chevy 203 range boxes, if there is i will source a chevy one. I plan on checking out and comparing the dodge 203 range to the chevy 203 range when i get home, just thought i would ask here maybe save some time thanks -troy-
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Don't forget you'll need new driveshafts front and rear too...more $$ and possibly more down time waiting to have them built.

    Rene
     
  7. tlspeed

    tlspeed Registered Member

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    Like i said i am a DIY guy, I have built my own drive shafts, and will build them for after the doubler, but probably will be square d-shafts this time. I am just trying to find out if the bolt pattern of the range box and shaft coming out of the range box in dodge version of the 203 is the same as the chevy version of the 203. Thanks guys -Troy-
     
  8. mouse

    mouse 1/2 ton status

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    Stephen at ORD told me that the doubler setup is about 1 inch linger than a 203 by itself......I'll probably use my zero rate to relocate the rear axle back one inch to compensate and keep the driveshaft the same.

     
  9. NorthWestFab

    NorthWestFab 1/2 ton status

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    The GM and Dodge NP203 range box only differ due to input gear spline count, Dodge is 23, GM TH350 type is 27. The gears will swap from one casr to the next.

    -Jordan
    NWF.
     
  10. tlspeed

    tlspeed Registered Member

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    Thanks Jordan, you are the man. Greatly appreciated. Do you know if the bolt patterns are the same, or in other words could i use the dodge range box as a template or mock up. thanks again. -Troy-
     
  11. NorthWestFab

    NorthWestFab 1/2 ton status

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    Bolt pattern on the back is the same as well as the front, mock up will work.
     
  12. tlspeed

    tlspeed Registered Member

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    Thanks again.
     

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