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NP 205 info needed...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by jekbrown, Aug 28, 2001.

  1. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    I have searched Ck5 and some other sites and am having trouble finding info....if there is a tech artical here someone please slap me upside the head and lemme know. ;)

    At any rate, I want to get rid of that poopy slip yoke 208 and use a 205 which would be behind a Jet Performance T700 (their 700r4) slush box. Questions...

    1) From what I understand I will need an adapter...who are these "advanced adapter" guys...and do they have a www site or anything?

    2) I was checking out ORDs info on 205 input gears, which were better...which were worse...etc...if I use an adapter...will I be stuck with one of these less desirable inputs...or do they make adapters that work with pretty much anything?

    3) if I go looking for a used 205...what should I be looking for...with respect to features and undesirable wear etc?

    Thats it for now...like I said before, if this info is already on ck5 I apologize..I couldnt find it! =(

    Any help at all would be greatly appreciated! Thanks!

    Jason
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Automatics are not my strong suit...but i'll give it a go. The 700R4 has a 27 spline output just like the TH350. The NP 205 mated to a TH 350 is reasonably common and would be the particular case you'll need. On adaptors I'm not sure, Advance can set you up but they are spendy and I seem to recall there is an easier way.

    The only 205 to shy away from would come out of an '80 model truck. These all have slip yoke rear outputs. As far as I know every other 205 has the fixed yoke.

    About the only thing I did to check my 205 when i found it was check the fluid level and condition. Its 90 weight gear lube just like a dif and should be clean if it was reasonably looked after. I moved the shifter through each position and spun the input shaft by hand to make sure it was doing what it was supposed to. The shifter should move between ranges with 'normal' effort and you should feel slight detents for each position. There is not really much that can go wrong with them...[​IMG]

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
     
  3. u2slow

    u2slow 1/2 ton status

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    Get ahold of an NP205 from a TH350. All you need is a shorter output shaft for the TH700 - otherwise it bolts right on.

    Nothing wrong with '80. It might well be your BEST source for this version of the NP205. It *may* have a slip-yoke, but an entire fixed-yoke can be swapped in from a less desireable 205 - Ford, Dodge, GM, whatever.
     
  4. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    The TH350 to NP205 is NOT reasonably common (just ask me how I know [​IMG]). The only years it happened was in late 79 and 80 when everything came through with an NP205 T-case. Before and after that, the only tranny's that came with the NP205 is the TH400 and manuals (mostly 1-ton variety). Advance adaptors sells the short 700r4 output needed $$$ to mate it to the NP205, but if you look at the footnote on their webpage, you need to buy (or aquire) the original TH350-NP205 adaptor (GM part number is 6273963 and lists for $294, dealer prices is $257, and <a target="_blank" href=http://www.gmpartsdirect.com>www.gmpartsdirect.com</a> is $208.15 shipped to your door).
    Hope this helps.
    Chris

    There is a Right way, a Wrong way, and then there is My way. The latter is usually the most fun! [​IMG]
     
  5. RedDwarf

    RedDwarf 1/2 ton status

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    Early 70's GMC rigs with the TH 350 all used the NP 205.

    Lift It, Lock It, LIVE IT!!!
     
  6. Blazer1970

    Blazer1970 1/2 ton status

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    A zillion '69 - '72 GM trucks had TH350/NP205 combo.

    Tim

    70 Blazer CST 4X4 350 SM465 NP205
    87 Burb 4X4 350
    01 GMC 2500HD 4X4 Duramax/Allison
     
  7. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    If I remember correctly the early 70's rigs used different frames, different cross-members, and different height and style adaptors that will not work with the new style crossmember/frames. I guess I should have been a little more specific. If anybody knows different for 73-87+ please let me know. As every GM source I have checked into has told me this.

    There is a Right way, a Wrong way, and then there is My way. The latter is usually the most fun! [​IMG]
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Hey Chris
    <blockquote><font class="small">In reply to:</font><hr>

    Automatics are not my strong suit...but i'll give it a go.

    <hr></blockquote>
    I knew I would be getting corrected on some of my reply, thus the disclaimer. [​IMG]

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
     
  9. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Rene,
    No problem! Sorry, but I do not know it all either [​IMG]. I didn't mean it as trying to "correct" you, like some people have done to others in the past (ala Executioner), I have just spent months trying to find an NP205 to TH350 adaptor to fix my current situation (I snapped mine [​IMG]), and wanted to let the guy know it MAY not be easy. The one I had is (I mean was) bolted to a 700r4. I have been able to find several people who have the old (pre '73 adaptors) which I guess are fairly plentiful, but have not been been able to find the '73 + adaptors after extensive searching. I did run across a GM parts guru in my search that said I would have a hard time considering the units were only produced in late '79 and '80 for the style I was looking for. I could use the earlier ones, but it would take some "engineering".
    I didn't mean to offend anyone if I did, it was put out more as an FYI. It was something I did not know until recently, much like the whole slip yoke 205 deal (mine is an 80 and I used to think all NP205's were slip yoke [​IMG], whoops). Since then I found a NP205 with fix yoke for $50 [​IMG] and converted.

    P.S. Thanks for all the welding info.


    There is a Right way, a Wrong way, and then there is My way. The latter is usually the most fun! [​IMG]
     
  10. californiak5

    californiak5 1/2 ton status

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    Hey Rene,

    [​IMG].............Happy B-Day.................[​IMG]

    See Ya,
    Keith

    [​IMG] <font color=green>Born to Drive My K5</font color=green> [​IMG]

    <a target="_blank" href=http://coloradok5.com/gallery/californiak5>CaliforniaK5's Pictures</a>
     
  11. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    No big Chris...I didn't know they were kinda tough to find until you pointed it out. I find out new stuff every day, and this is how it happens. Thanks for the heads up. Did you ever check into the cost of using Advance Adaptors? I know for some stuff they can be spendy...but for something like this it might be worth it.

    Keith...sssshhhh I was trying to avoid aknowledging my B-day.[​IMG] J/K! thanks!

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
     
  12. Triaged

    Triaged 1/2 ton status

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    Do you know what the difference is between the pre 73 and the later th350 to np205 adapter? Just currious.

    '71 Blazer CST w/ a 400sbc, 4" lift, 36" Supper Swampers, and alot of rust
    <a target="_blank" href=http://community.webshots.com/user/triaged>See it Here </a>
     
  13. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    You can use ANY TH350 version 205, we haven't seen any difference in the adapters, other than the early versions use a bearing in the adapter which is nice to have but far from essential. I ran a 205 from a '72 in my K5 for several years with a TH700 and the Gen1 doubler.
    You will need the short ouput shaft from Advance Adapters. We carry them for about $160.00.

    The 27 spline shaft is not a bad setup, it's pretty fine and wears reasonably well, and torque strength is pretty good also. They do break occasionally, but not that often.
    If you have trouble finding the 205 and/or the parts, we do carry them, but they are expensive. I think the adapter prices outlined by someone above are out of date, GM increased the price of these by about 50% not too long ago. Hate to throw in a blatant plug for the Doubler here, but you could end up wasting some money on the 205 adapters that you won't use if you do go to the Doubler later, so it might be more economical (not cheaper) to look into the Doubler to start with. TH350 version 203's are almost a dime a dozen still.

    Making the world better, one truck at a time.
    SW-ORD
    <a target="_blank" href=http://www.offroaddesign.com>www.offroaddesign.com</a>
     
  14. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    I did not give them a call, but on their website they list an "adaptor" to mate a 700r4 to a NP205 for vehicles originally equipped with a TH350. When I looked at the listing for the "adaptor", it showed that is was a short output shaft for the 700r4 transmission (p/n 50-6900), with a footnote stating "this adaptor works together with your stock adaptor". I have not called them to find out if they offer the "stock adaptor", but I will put it on my list of things to do tomorrow at work [​IMG], and let everyone know.

    P.S. Happy Birthday!

    See my rig at <a target="_blank" href=http://coloradok5.com/gallery/Leadfoot>http://coloradok5.com/gallery/Leadfoot</a>
     
  15. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Stephen have you seen the new and old adaptors side by side? The GM dealer lists them as two different part numbers (unless he didn't know what he was talking about). There were also different part numbers for the mounts that hold it to the crossmember, so I assumed they were different (not to mentions the crossmembers and frames being different). Guess I look like an a$$ don't I [​IMG]

    Hey, I learn something new everyday, that why I love this site.

    See my rig at <a target="_blank" href=http://coloradok5.com/gallery/Leadfoot>http://coloradok5.com/gallery/Leadfoot</a>
     

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