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NP205 adapter seals help

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by dbozman, Jan 27, 2007.

  1. dbozman

    dbozman 1/2 ton status

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    Can anyone clarify the seals I need on the adapter from a T350 to an NP205 in my 74 K5? Dumped the 203 and got a 205 and adapter from another K5.

    Trying to make sure my T350 doesn't dump ATF into the tcase. The adapter does not appear to have a seal on the tranny side, other than the big O-ring. On the case side it has a typical paper figure 8/racetrack pattern where the adapter/case mate.

    Are there more than the one seal and O-ring? Thanks for any clarification and part numbers. Something I can get from NAPA?
    d
     
  2. dbozman

    dbozman 1/2 ton status

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    No one?

    On Pirate, I was advised there's only the backside seal and the O-ring. Anyone concur? Or not?
     
  3. 83silverado

    83silverado Newbie

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    There should be a seal inside the adapter on the shaft collar. Then just the o-ring and the gasket.
     
  4. FWP

    FWP CRS

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    I'm curious myself. Is there any evidence of an original seal in the adapter ID?
     
  5. dbozman

    dbozman 1/2 ton status

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    I ended up just taking the adapter apart. There are two regular oil seals inside on mine (be aware their are at least two different styles of T350 adapters). Got those from Napa. Reused the O-ring and got a new figure-8 gasket from ORD. No one, and I mean no parts house in Phx., had that gasket.

    Just got it mounted yesterday. Will likely see today if it leaks or not.
    d
     
  6. Jimbo*

    Jimbo* 1/2 ton status

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    There are actually four seals between the TH350 and NP205:
    1. O-ring on the 205 input shaft
    2. Double lip seal between the adapter and drive sleeve
    3. O-ring between adapter and TH350 case
    4. Gasket between adapter and 205--this needs to be used because the adapter has machined reliefs which dictate spacing to locate the 205 bearing and snapring

    As has been said, there are two different styles of TH350/NP205 adapter, the difference being one has a support bearing for the drive sleeve, but the later models did not have this feature. However, the number of gaskets and seals does not change.

    Jimbo
     

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