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th350 and th400 and np205??

Discussion in 'The Garage' started by chevy_mud_84, Jun 26, 2005.

  1. chevy_mud_84

    chevy_mud_84 Registered Member

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    I have a th350 that has a np203 attached to it, and im swapping it for an np205. I already have the 205 sittin in the garage. But now my question is.....the truck that i took the 205 outta was an 1980 3/4ton chev, and i think it had a th350 in it as well, but then i got told that both the th350 and 400 are 3 speeds. Which i didnt know, i thaught only that 350 was. So is it true they are both 3 speeds cuz i never looked at the oil pan too see which one it was i just went by the number of gears it showed. So if it was a 400 and not a 350, will this 205 still bolt up to my 350 or no? I took the adapter, that was used on that truck aswell, so i have all the parts, but need to know whether it'll work or not. Thanks and sorry for the long question, im just tryin to get this all done and figured out before the next 4x4 comp. this summer.
     
  2. thatK30guy

    thatK30guy 1 ton status Premium Member

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    3 speed on automatics means "L, 2, 1" with 1 being the direct 1 to 1 ratio which you put in drive. If it were an overdrive auto, it would have read "1, 2, 3, OD" or something like that.

    A 205 behind the 350 or 400 will not interchange due to the input shaft variations. You can have a 350 equipped 205 machined to fit a 400 by boring the bearing hole a larger diameter and swapping in the correct input shaft, but you can't make a 400 equipped 205 fit a 350.
     
  3. icer97

    icer97 1/2 ton status

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    If its for a 400, It wont bolt up to the 350 tranny. Different input shaft splines.
     
  4. icer97

    icer97 1/2 ton status

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    Beat me to it! :grin:
     
  5. chevy_mud_84

    chevy_mud_84 Registered Member

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    Dammit!!! It better be off a 350. I guess i better go find that truck in the junk yard again. If it is from a 400 is it possible to buy and adapter plate? if so any ideas how much, and where?
     
  6. thatK30guy

    thatK30guy 1 ton status Premium Member

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    I'm working out details with icer right now to buy his 400/205 combo. All I really need is the 205 for a Doubler project and the 400 for my K30 which blew holes and cracks in the bellhousing. I need a replacement housing for swapping my 400 internals over to the new housing.

    Now if you, me and Icer can come to terms here, I would be more than happy to let Icer and you work out a deal for the 400/205 adaptor from him providing he knock off the price from the 400/205 combo.

    Let me send him a PM. :deal: :waytogo:
     
  7. NorthWestFab

    NorthWestFab 1/2 ton status

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    You dont have to go back to the yard and look at the truck. The differences between a TH400 NP205 and a TH350 NP205 are quite easy to identify. TH350 version NP205s will have a male 27 spline input and the adaptor would have came with a 27 spline coupler. If it is a TH400 version it will have a 32 spline female input gear. If you do accidently have the wrong version your not out of luck as the TH400 version is a fairly desirable case and im sure you could sell it on this board and re-coup more then enough to find the proper case.

    Jordan
    NorthwestFab
     
  8. icer97

    icer97 1/2 ton status

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    I have the adaptor, PM me and maybe us 3 could work out something. :grin:
     
  9. sweetk30

    sweetk30 professional hooker Premium Member

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    even easyer way to tell that no one told was th350/th700 use 4 bolt holes to tranny on adaptor. th400/4l80-e use 6 bolt holes to hole tranny to tcase adaptor. and also what northwestfab said on the spline count and setup.
     
  10. chevy_mud_84

    chevy_mud_84 Registered Member

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    Yes!!!

    Sweet ok, im happy now!! So ya mine has the 4 bolts for the adapter and it has a 27 spline shaft, that means its for a th350?? if thats so, then im in luck.
    Thanks guys. you've just made my day.
     

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