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NP205 HELP

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by KRAZIE87K5, Apr 4, 2001.

  1. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Alright. I just dragged out the NP205 from the garage with the intent to figure out a way to get it installed. The thing is pretty heavy for starters, but I have a trans jack so its all good. The question I have is... WHERE DO I START??? I bought this damn truck, and I knew nothing of 4x4 trucks. I am learning now. Anyhow, I have no interior parts (IE the floor mounted box with position indicators and whatever else belongs between the driver and xfer case) and need to know what I need to acquire to get this thing to work. The 454 is almost ready to go in, and the TH350 is ready to go (get torched) as well.

    The xfer case was acquired from somewhere before I bought the truck, but it is in working order supposedly. What can I check out on this thing to be sure its OK? Also, what are good items to replace for maintenances sake? AND what kind of vehicle can I tell the parts place that I have to get the right parts? Check my webpage for pics of the xfer case in the "photos" section.

    Finally, does anyone know of a webpage where I can get identification info for transfer cases? I don't even really know if this thing is a NP205 or not. I am the greenest of green, so please bear with me here. Thanks guys and gals.

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  2. dyeager535

    dyeager535 1 ton status Premium Member

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    There will be a tag on the tranny, facing the front of the vehicle, as installed in the truck. Should say "205" and 1.96 ratio or something similar on it. Round tag. Might be covered in crud. The 205 has two shift "rails" that also face forward as installed, on the passenger side. The shift lever itself bolts to the "adapter", the metal piece that joins the tranny and transfercase.

    If you wanted to make sure it didn't leak, you could pull the yolks off and replace the oil seals there, as well as all the cover gaskets. I wouldn't go so far as to remove theinput/output assemblies and replace those seals, they don't see any wear or pressure.

    By putting it in 4wd (push both rails into the case as far as possible) you could check to see how much "slop" there is between the input and output shaft(s) and feel for any kind of binding. Other than that, put it in and hope it works. You'll know when you start driving if its bad or not. Rarely will you see a problem with these transfer cases. (if it is indeed a 205) They weigh about 75lbs and have a 1 piece cast iron case always I *believe*...

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  3. Wheels

    Wheels 1/2 ton status

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    Looked at your pics and you have an '80-up slip yoke NP 205 with a TH350 adaptor. Also the center top picture is what is reffered to as a support strut. It bolts on the right side of the t-case (two bolt holes) and the other end bolts up to the bolt hole on top of the guide pin at the bellhousing. The strut may be from a NP203, and if it is, it will have to be shortened. Bolt the t-case up to the tranny and check it for fit befor you get it installed. With out it, you may crack the tranny housing.
    Now for the NP205. On the top side, above the outboard shift rail, there should be an electrical switch. This is your 4-wheel switch that lights up a light on the dash (tach side about the 6:30 position). On the shift knob is the shift pattern (from full back: 4-hi, 2-hi, N, 4-lo). That is your only shift indicator. If you pull the switch, there should be a spring and a detent ball so be careful if you remove this and don't loose the parts. There is a reseal kit that the only place I found one here in OKC is at Blumenthal Manufacturing (405) 232-9557, 800-262-9557. Talk to Rodney, he's the 203 and 205 guru there. The reseal kit was about $27. Check to see if you have a manual transmission supply or rework place around your area. If you call Rodney, tell you have a New Process 205 with a slip shaft that bolts to a TH 350 transmission, and what you need. He'll take it from there. For parts house questions, rfere to a 1908 or a 1981 Blazer, 4wheel drive (they'll ask this), TH 350, 350 cu in motor, etc and you need the part for the transfer case.....good luck on what you get from them unless you have a person that has a 4x4.
    I didn't notice if you had the bolt that holds the shift handle on or not. Should have a 13/16" head and a zerk (grease) fitting in the middle of it, the shank has a turned down section in the middle of it and then threads. There's also a flat washer and a wavy washer that goes with it. Need this to bolt it up to the adaptor. Also, there ehould be a piece of rod about 3" long that hooks the shifter to the shift rods. (If you don't have it, let me know, I have one left over).
    For a good repair manual, get the Chilton Truck Repair Manual and look in the Drivetrain section under Transfer Cases. It has a pretty good breakdown of the 205 with names to all the parts. The haynes manual for the Blazer has one too, but it's just a tad smaller and my arms are just a little too short. Good luck. I just finished rebuilding one and bolted it up to a 700R4 (replaced the TH350/NP203). Also, check and see if you have manual, automatic or locked hubs. Manual will have a selector in the middle of them, Automatic will have 6 allen screw on it and 4X4 stenciled on them, and locked will have a pop on cap, generally speaking.
     
  4. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    That info is great. Now for more questions. This trans has no "lock" position then? The "top side" parts... well I have none. The guy didn't give me any. I need to acquire all the crap to get that xfer case installed. I have no shift knob. Where can I find one? Junk Yard? Finally, is that xfer case as tough as I hear? The 454 I plan to mount to it will be strong, and I was hoping to be able to beat on it without worrying. Are there any good webpages for more information on this transfer case?

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  5. dyeager535

    dyeager535 1 ton status Premium Member

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    You could probably run 1000HP plus through that case before you even had to start thinking about it as a weak link compared to everything else in the drivetrain.

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  6. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    1000HP??!!!! You just put a big fat smile on my face! That is what I wanted to know. All I need to know now is, whats the next weakest link then? U-joints?

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  7. dyeager535

    dyeager535 1 ton status Premium Member

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    I'd have to say axles and u-joints. There are plenty of guys here running motors much more powerful than mine...they'd be better ones to comment on that though. My dads relatively stout 454 hasn't hurt his 205 a bit, and I beat on it hard when I drive it sometimes.1000 might be an exaggeration, but probably not much, and you'd have to have a pretty incredible motor to be putting out anywhere near that much.

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    The 205 is King Kong strong [​IMG]
    With a 454 I think your next weakest link is the TH350, unless you have 10 bolts front and rear. I hope your TH 350 is built up somewhat, I've heard they can be built to survive. If you do have 10's front and rear they will be your weak link, moreso with bigger tires.

    Rene

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  9. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Go to the nearest GM dealer and have them order part number 15648946. This is a BRAND NEW NP205 shifter knob. Its the heavy type knob. They cost around $15.00.
     

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