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Discussion Starter · #1 ·
So some time next week I'm going to be replacing the fluids in both my front diff and transfer care on my 1996 Tahoe. The front diff calls for 80W-90 GL-5 gear oil and the t-case calls for dexron III or superseding. I'm gonna use dexron IV which should be the superseding fluid. It is not an automatic t-case.

Any advice while doing this change?
 

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The only advice I have is to make sure that you can get the fill plugs out before you drain them. I also use a piece of cardboard when I drain the front diff. I crease it down the center and lay it on an angle between the drain plug and my drain pan making a trough or ramp for the oil to roll down. This stops me from having to pull my skid plate or covering my skid plate in oil.
 

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Discussion Starter · #3 ·
I'm doing it on a lift at school so removing the plate is easy, its a size 15 mm. I always remove the fill before the drain. Just need to make sure my friend helping knows the same. Do you know the approx size of the t-case drain and fill plugs because they look very large...
 

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the t-case calls for dexron III or superseding. I'm gonna use dexron IV which should be the superseding fluid. It is not an automatic t-case.

Any advice while doing this change?
I agree, you do not have an auto t-case; however, if you have push buttons (and not a shift lever on the floor) you still have clutches. These clutches need Auto Trak II fluid. If you have a manual floor shifter, the ATF will probably work.
 

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Discussion Starter · #5 ·
I have the push buttons. So you are saying I should use the Auto Track II not the Dexron IV. Poop that would make this change 10x harder because no one sells it in the area. Advance and autozone don't stock it and I don't have an O'Riley's. So the only place to get it would be Chevy where they would mark it up.

BTW in the description of the product it says for Automatic T-cases not regular ones, but since my truck was built in a time of t-case design change I have no clue.
 

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My understanding is manual or clutches. The fully auto cases (like in a Caddy) are not much different from the push button case that you have, they use the same clutch packs. Again, as I understand it, the clutches need the additives that are in the Auto Track II.

Try going to the NPG/NVG (I don't remember if New Process, or New Venture is the current name) web site, maybe they have more info.

Do you have an Owner's Manual?
 

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Usually I hate getting stuff at the stealership too but when I went for the autotrak fluid the price/qt was actually similar in price as any decent synthetic fluid.
 

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Discussion Starter · #8 ·
My understanding is manual or clutches. The fully auto cases (like in a Caddy) are not much different from the push button case that you have, they use the same clutch packs. Again, as I understand it, the clutches need the additives that are in the Auto Track II.

Try going to the NPG/NVG (I don't remember if New Process, or New Venture is the current name) web site, maybe they have more info.

Do you have an Owner's Manual?
My owners manual says Dexron III or superseding fluid. I have the NP241 electronic transfer case. The New Venture site says my product doesn't exist.....
 

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My owners manual says Dexron III or superseding fluid. I have the NP241 electronic transfer case. The New Venture site says my product doesn't exist.....
I would think that if thats what the manual states you will be good. When did they even start using the Autotrak? Maybe the 1996 is pre autotrak fluid.
 

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Discussion Starter · #10 ·
I think the first Auto-Trak T case was in 98 on the Tahoe and Burban.
 

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Discussion Starter · #11 ·
I lied its the NP243 t-case. I bought the fluids today as well as took some current pics.

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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.
 

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

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.
 

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Discussion Starter · #13 ·
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.
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.
 

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I think the first Auto-Trak T case was in 98 on the Tahoe and Burban.
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..........
 

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Discussion Starter · #16 · (Edited)
does the front diff. need the posi additive like the rear one does?
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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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....
 

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Discussion Starter · #18 ·
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....
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.
 

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Discussion Starter · #20 ·
Ok sounds good!
 
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