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I am looking to buy a 99 K2500 burb and I was wondering what t case it has and if anybody has had any issues to be aware of with that t case. The truck has the electronic 4x4 shift buttons instead of the manual shifter. I would prefer the manual shifter, but that is the only thing I don't like on this truck.
 

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I am looking to buy a 99 K2500 burb and I was wondering what t case it has and if anybody has had any issues to be aware of with that t case. The truck has the electronic 4x4 shift buttons instead of the manual shifter. I would prefer the manual shifter, but that is the only thing I don't like on this truck.
I believe the transfer case is a NP246
 
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The difference in the push button ones is if its got the 'auto 4x4' option. I think all the electronic cases after 97 were the ones that had the 'pump rub' issues where the oil pump moves around and wears through the case causing a leak which after the level gets low enough causes the case to self destruct. Aftermarket makes replacement case halves and pump upgrades to keep it from happening again.

The auto cases have to use the blue selec trac fluid. Others don't have to but I like using it because its blue so its easier to identify where puddles came from.
 
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And the electronic part doesn't seem to be that big of a failure point. Biggest failure point in the system has always been the front axle actuator which was the same for floor or electronic shifting. 99 I think would have had the motor unit from the factory rather than the really early vacuum or 90's thermal unit.
 

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Besides the oil pump issue.
The encoder(high low shift motor) is also a problem. If it is stuck in gear or wont shift with 4x4 lights blinking.
Encoder is not that hard to replace. The unit unbolts from the xfer case. do not need to disassemble the case.
Usually all you need is a new encoder ring and seal. $50.. or so in parts. Or all new unit will cost around $ 200.oo. Its a common problem there are utube vids covering it.
Your 99 should have the motor drive front axle actuator. They are the best kind. GM 4x4 after 96 had the actuator motor upgrade.
 

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Discussion Starter #6
Thanks for the advice. I have been doing research and I am planning on removing the t case and doing the pump upgrade at some point before I put too many miles on it.

Tell me more about the blue fluid? Don't they usually take ATF?
 

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They did until the 'auto' ones came out. That was when the blue Auto-Trac fluid came out too. It supposedly has some special stuff in it for the clutch that makes the auto thing work and if you use regular Dexron it won't last very long. I have heard its pretty much just synthetic ATF but since its not like you need gallons of the stuff I usually just buy the actual stuff.
 

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Discussion Starter #8
What brand of fluid do you use for the t case?
 

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Valvoline makes a fluid for NP246 and others. They call it Mutiple Vehicle transfer case fluid. Make sure it is says Full Synthetic on the bottle. It will list it as a replacement for GM Trak 2 fluid on the back of the bottle.
Or just go to GM and buy AC delco Auto Trak 2 fluid. You can also find it many places on line.
 

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Some parts stores have the GM stuff too. I never compared prices of that and the other compatible fluids. Originally when only GM sold it it was pretty expensive but they don't take that much and you don't have to change it that often so not that big a deal in the long run. Auto Trak 2 is the key word you are looking for. That supposedly means its got the magic sauce needed for the proper operation of the auto clutch.
 
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I am looking to buy a 99 K2500 burb and I was wondering what t case it has and if anybody has had any issues to be aware of with that t case. The truck has the electronic 4x4 shift buttons instead of the manual shifter. I would prefer the manual shifter, but that is the only thing I don't like on this truck.
I have a 1999 GMC Denali Gasser 5.7 with push button 4WD with 205K and Ive never had and issue with the transfer case not shifting or the system itself. I did however have to replace my tranny 4L80E at 145K because the sungrear went bad. Bought 4L80E GM rebuilt with all the updated upgrades and it still running great.
 
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