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NP 203 help needed

Discussion in 'The Garage' started by SchnorrCS, Jul 23, 2006.

  1. SchnorrCS

    SchnorrCS 1/2 ton status

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    Ok heres the question...
    I have the rear most "cone" off the trans case. It aluminum and houses the rear output roller bearing and the Speedo gear as well as the output shaft oil seal. It also has a hole on the very top. About 3/8ths of an inch, and I don't know what the hell it's for. The only thing I can think of is a vent, but that doesn't make sence, cause the inside of the cone under the hole is all padded and stuff. Little help?

    cS
     
  2. dremu

    dremu Officious Thread Derailer Premium Member

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    Uhh ... aluminum? Thought '203's were cast iron, and 208's were aluminum.

    Post up a pic of the 'case and maybe another of the location of the hole?

    Should be just one vent, suitable for connection to a hose, but I donno where they are on '208's.

    -- A
     
  3. justhorsinaround

    justhorsinaround 3/4 ton status

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    205s are cast iron.
     
  4. dremu

    dremu Officious Thread Derailer Premium Member

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    Well, yeah, but I thought '203's were too.

    Ohhh, wait, this may have been covered ... I think later '203's had the aluminum cone. All I know is my '74 '203 was FREAKING HEAVY.

    Not as bad as a 203/Doubler/205, but still heavy.

    -- A
     
  5. justhorsinaround

    justhorsinaround 3/4 ton status

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    They're not as light as a 208 but they are aluminum. Course this isn't helping out this guy at all.:haha: My best guess would be a vent. Wadding to keep the fluid in but still let air get in and out?
     
  6. southern85

    southern85 Newbie

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    the 203 is cast but has a alum tail. also the rear vent has a foam pad inside rear cone
     
  7. SchnorrCS

    SchnorrCS 1/2 ton status

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    Must be a vent then, cause it does have some padding in there. Why would you want5 to pad a vent hole?
    What do you guys think of tapping that hole and putting a barbed fitting and a hose to extend it so water doesn't get in there. Thanks for all the replies.
    cS
     
  8. mouse

    mouse 1/2 ton status

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    Yes, its for a vent. It should have a steel nipple in the hole, but they are not retained by very much, making them easy to fall out if you're not watching while removing the TC. BTW, all 203's have aluminum tail housings - I've got 2 right now, ones a 1974 vintage, and the other is a 1977, same thing.
     
  9. blazinzuk

    blazinzuk Buzzbox voodoo Premium Member GMOTM Winner

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    1973 vintage ones at least mine have the cast iron tail housing that is one peice not two

    I put a fitting in the hole and ran a tube up to the engine from it
     
  10. 76jime

    76jime Registered Member

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    A picture is worth........

    Jime.jpg
     
  11. b454rat

    b454rat 1/2 ton status Premium Member

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    That is the vent hole, the foam is there to keep fluid from coming in or out. It's also the location to drill and tap for VSS.....
     
  12. SchnorrCS

    SchnorrCS 1/2 ton status

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    VSS??? Never heard of it. Or I'm retarded
     
  13. mouse

    mouse 1/2 ton status

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    Vehicle speed sensor - used when a fuel injected truck runs a K5 and can't use the speedo mounted VSS.

    Its not a stock option.
     
  14. SchnorrCS

    SchnorrCS 1/2 ton status

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    I see. Thanks for clearing that up.
    Here's another question. Anybody got any tricks for removing the front output shaft/yoke seal? The rear was a pain and I had the cone off. I'm trying to cure all my leaks. Tread lightly, ya know?
    With the rear I had to heat the cone up to break the locktight seal. I'm not going to cause any needle bearings to fall out or anything doing the front while the case is still in the truck am I? and how about the rear "plate" that has about 8~10 bolts holding it in. I wanna say it's to hold the chain drive gear in or something. Trying to replace the gasketsI can while it's still on the truck. I'll have to rebuild the tranny in a year or so, and I'm trying to avoid pulling it until then. I have just never done a 203 before. Thanks for the help fellas.
    cS
     
  15. 76Hillbilly

    76Hillbilly Registered Member

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    np 203 is a cast iron case. 300# to be exact. hope the info helps
     
  16. SchnorrCS

    SchnorrCS 1/2 ton status

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    Once and for all....No one is arguing that the case is cast iron, but the differential housing and tail cone are made out of aluminum. Any input on the questions?
     
  17. mouse

    mouse 1/2 ton status

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    I re-sealed a 203 this spring. The bearings at both drive flanges are large round bearings residing in a cage setup. If they fall out, they are shot and need replacing, so don't worry. The front output flange comes off like the rear, remove the large center nut, then the bolts on the cover. Use a drift to knock out the old seal, tap in the new seal. I like to use a little "Right Stuff" around the seal to housing for extra sealing. Also, a little under the large nut to seal the spline.

    Under the adapter is just a regular seal. Use a seal puller to remove and tap in a new one.
     
  18. SchnorrCS

    SchnorrCS 1/2 ton status

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    Cool. Thanks alot.
    How about the little rubber ring under the front bearing retainer? Anybody got a part number or anything? I called a dealer, and even they didn't know anything about it.
     

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