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th350,th400,200r4,700r4 - np203,np205,np207,np208?

Discussion in 'The Garage' started by swamp donkey, Oct 17, 2002.

  1. swamp donkey

    swamp donkey 1/2 ton status

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    I'm sure everyone is sick of my auto tranny questions by now, but I have learned allot (and the more I learn the more I realize I don't know).
    Can someone break down the above tranny's/t-cases for me? I understand that the 350's and 400's are 3speed and the others are overdrive, but other than that... what should I know, and if I am converting my daily driver to auto from 4 speed, what combo do I want?
    As a side note, if the tranny I get does not have a torque converter which one should I get?
    Thanks a trillion billion.
     
  2. zakk

    zakk 1/2 ton status

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    best cheap Auto combo: TH400 + NP205

    best expensive auto: Allison + 205 (not sure if it would work)

    Best manual: 465 + 205
     
  3. GMslave

    GMslave 1/2 ton status

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    </font><blockquote><font class="small">In reply to:</font><hr />
    Can someone break down the above tranny's/t-cases for me? I understand that the 350's and 400's are 3speed and the others are overdrive, but other than that... what should I know, and if I am converting my daily driver to auto from 4 speed, what combo do I want?


    [/ QUOTE ] I'll assume you have a good reason for why you are converting, so here's my question "What do you want your truck to do?" What are you willing to live with? How much can you spend? (ok that's more than one question, oh well)
     
  4. swamp donkey

    swamp donkey 1/2 ton status

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    GMslave,
    Yeah I have a good reason to convert, I hate to shift. I live in Los Angeles, and with traffic the clutch is a killer.
    As far as my plans, maybe some sand dunes, other than that just a daily driver.
    As far as budget goes, I have squat. I am looking at buying a used combo, and hoping to get the whole thing and install it (minus shifter) for $500.
     
  5. GMslave

    GMslave 1/2 ton status

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    IMO, you should look at a th 350 with either 203,205, or a 208. The 203's are heavy as HELL, so be warned. I just installed mine back into my truck by myself, big suckfest. You probably won't find a 350/205 combo for cheap but if you do grab it. Same with a 400/205. I ran a 350/208 combo in another project, which held up pretty good (2 years) but when it let go, it was beyond ugly. Besides, a 208 will need a different rear shaft (slip yoke). A TH700 will probably be out of your price range if you have to get it rebuilt, but it comes with a 3.04 (?) first gear, which is /forums/images/graemlins/thumb.gif off road. I run a 350/203, with a TCI 2000 stall converter. So far, I like it. It gets the revs going just enough before it really takes off, since I'll never go in the rocks, it works.My .02
     
  6. 84k5

    84k5 1/2 ton status

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    203=full time chain drive..most have been converted to part time though about 2:1 low
    205=part time gear drive about 2:1 low
    208=part time chain drive, aluminum housing, slip yoke,2.6:1 low

    the 400 is pretty much a beefier version of the 350
    the 700 has od, but is weaker. later versions (after 85 i think?) are better. what ever you get put a cooler on it. good luck.
     
  7. zakk

    zakk 1/2 ton status

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    actually

    a 203 is 2.1:1
    a 205 is 1.96:1
    dunno what a 208 is, never even seen one /forums/images/graemlins/grin.gif
     
  8. thatK30guy

    thatK30guy 1 ton status Premium Member

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    What about the 475 turbo tranny? Its the motorhome 400 tranny thats a lot stronger than the 400. /forums/images/graemlins/wink.gif
     
  9. BLUESMAN

    BLUESMAN 1/2 ton status

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    The most common trans/t-case you are going to find behind an K/5 will be the TH350/203.Not a bad combo.The driveshafts be sure and pick them up too,seems every other combo of trans/t-cases are different lengths.You should be able to pick up the trans/t-case and shafts for under $500.The other combo prob would be the TH350/208.The 208 is alum. and has an 2.62:1 lo-range(205 is 2.0:1).I agree with others on the TH700,the good ones are '88 and up and are costly to rebuild.Find someone to swap your manual for an auto set-up....you might actually make some $ on the deal.Good Luck!
     
  10. swamp donkey

    swamp donkey 1/2 ton status

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    I found a 350/203 combo mated together with torque converter. $200 for everything. The 203 has no 4-hi.
    Can I still use the 27 spline input (output?) shaft and adapter?
    What pitfalls am I looking at. I am picking up this tranny this weekend. If this costs me more than $500 (including a shifter) my wife will never let me work on the truck again - and I am only half joking.
     
  11. ol_grayfeather

    ol_grayfeather Registered Member

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    NP 208 is 2.6:1 and with the 700r4 3.06:1 first gear you can get pretty low...for stock

    Dan
     

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