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Front diff and t-case fluid change.

Discussion in 'Maintenance & Upkeep' started by Conlan Rose, Jun 12, 2013.

  1. Conlan Rose

    Conlan Rose Super Moderator 1000 Posts 100 Posts

    I lied its the NP243 t-case. I bought the fluids today as well as took some current pics.

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    IMG_20130615_211310_064.jpg IMG_20130615_211303_637.jpg

    Yah I mainly use Valvoline in the truck because they have all my needed fluids and are certified by GM to have Dexron IV and meet Dexros1 oil requirements. I just need to save and put Valvoline Dexron IV in the tranny and maybe do the rear end by summers end even tho it was done last year.

    Attached Files:

  2. steved

    steved Former Member 100 Posts


    IIRC, NP241 is the manually shifted version and the NP243 is the solenoid shifted version...it is not an automatic transfer case, it is simply a manual transfer case shifted by solenoids. ATF is what you want for a NP241 for sure...

    Pretty much all the NPs were designated this way...NP2X1 is a manual lever, NP2X3 is the solenoid shifted.
  3. Conlan Rose

    Conlan Rose Super Moderator 1000 Posts 100 Posts

    You are correct. There are no clutch packs like the Auto Trak t case. As you see I got the ATF and personally I got full synthetic Dexron-VI which is the superseding fluid of Dexron III.
  4. j cat

    j cat Active Member 1000 Posts 100 Posts

    I have the OEM shop manual for my 2000 silverado 4X4 PU. the fluid it says to use is DEXRON III. now on having a clunk issue with the drive shaft the service manager informed me that DEXRON III is not to be used in this transfercase. auto 4WD/4WD hi/lo 2WD push button .

    the fluid that was installed at the factory was the autotrac II. autotrac II costs the same as synthetic tranny fluid/QT. clutches need this type fluid.

    on your transfercase I believe GM now has a fluid that is specific for your transfercase. DEXRON III is now no longer a licensed GM fluid for any useage. also DEXRON VI is a lower viscosity than DEXRON III. The fluids are different.

    it is a little tricky so using your vin# the dealership will give you the updated correct fluid to use.

    always open the fill first before draining. never over torque these plugs as some have had the case crack..........
  5. K15 Blazer Guy

    K15 Blazer Guy New Member 100 Posts

    does the front diff. need the posi additive like the rear one does?
  6. Conlan Rose

    Conlan Rose Super Moderator 1000 Posts 100 Posts

    No because its not a posi but I might look for anti chatter additive because while testing the 4x4 in the heavy rain on decel the front chattered a lot.

    I filled the t-case with the exact amount of fluid that was recemended because all of the fluid came out, thanks to New Process' great drain plug design.

    I filled the diff until is was 1/2 an inch from the hole from what I could tell. May need to check again to make sure it has enough fluid. I did add about .5pts less then the exact amount of fluid.

    I will post pics soon its been a hell of a great day!

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    Last edited: Jun 18, 2013
  7. K15 Blazer Guy

    K15 Blazer Guy New Member 100 Posts

    very thorough! thanks!
    and crusty lol looks just like mine. im so glad I got that aluminum rear diff cover.

    does the front have some kind of electronic or momentum locking feature though? I though I read that somewhere....
  8. Conlan Rose

    Conlan Rose Super Moderator 1000 Posts 100 Posts

    It is electronic but only to engage the drive shaft. The front diff has no locking or limited slip functions in terms of the physical differential gears.

    And thank you. I will be trying to find one soon as well.
  9. K15 Blazer Guy

    K15 Blazer Guy New Member 100 Posts

    amazon was the cheapest.... ill post pics of if soon
  10. Conlan Rose

    Conlan Rose Super Moderator 1000 Posts 100 Posts

    Ok sounds good!

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