99 Suburban 2500/6.5 Transfer case Question

[vm4]

Hello all!

Got my first 6.5 Suburban after having an 87 350 and a 95 454.

Bought it knowing the transfer case was going to go sooner or later... which brings me to current question. I got a reman case from AER, I liked the warranty and price... Do i need to replace any seals or gaskets and does anyone know the type of oil and volume i'll need??

Many thanks, any and all advice is much appreciated!!

V

[Robyn]

Hi

If you have the electronic push button box then it takes AUTO TRAK 2 IIRC

There is likely an O ring or a gasket where the T case bolts up to the tranny.

[DmaxMaverick]

Hi

If you have the electronic push button box then it takes AUTO TRAK 2 IIRC......

ONLY if it's really "Auto 4x4" (NP246 TC). If a button is not "Auto 4x4" (NP243/263 TC, with only 2HI, 4HI, 4LO, N), then it's only an electrically shifted manual TC, requiring Dexron III ATF. If it has an "Auto 4x4" button, it requires Autotrac II fluid. If it has a floor shifter, it requires ATF, in any case.

[Robyn]

What is the difference in the fluid
Friction quality for the clutch packs ??

The older boxes are pretty easy to keep happy

[vm4]

Thanks!

I spoke with a local Chevy Parts dept. they said there eas a seal and a gasket that would be needed to be replaced, the guy told me I would need two quarts of Trak II...

It is push button( 2wd, 4hi, 4 lo). I understand thats the NP1 Designation... Any further thoughts?!

TIA

[DmaxMaverick]

Thanks!

I spoke with a local Chevy Parts dept. they said there eas a seal and a gasket that would be needed to be replaced, the guy told me I would need two quarts of Trak II...

It is push button( 2wd, 4hi, 4 lo). I understand thats the NP1 Designation... Any further thoughts?!

TIA



This requires Dexron III ATF. NOT Autotrac II fluid, unless it has the "Auto 4x4" button/option. Absent that feature, your is very likely an NP243/NV263, which requires Dex III.

"NP1" is the RPO code, indicating it is the NP243 (early/LD) or NV263* (late models/*XHD). All require Dexron III ATF. The RPO code for "Auto 4x4" is NP8.

Have a look at THIS WEBPAGE (http://www.justchevytrucks.com/partspictures/transfercases.html) for pictures and descriptions of the buttons and TC's.

The NV246 TC is a COMPLETELY different animal, compared to any other common TC. It has load balancing clutches, that balances front/rear torque. "Auto 4x4" is a lot like the (older?) Jeep systems, and why they can be driven on dry pavement without all the scrubbing (although not recommended for extended periods). The NV246 was an option on 2500(LD), 1500HD, and lighter trucks. I don't recall it being offered on GMT-400 8600+ GVWR trucks.

[DmaxMaverick]

What is the difference in the fluid
Friction quality for the clutch packs ??

The older boxes are pretty easy to keep happy

I suspect the difference, other than the color (blue) and the cost (3X), is just that. Problem is, the fluids are likely not the same viscosity, and clearances and component materials are different, to accommodate the different additives. I know if you use the wrong fluid in either, they will die an early death, especially if your TC has the plastic pump housing. Dexron III/IV synthetic ATF will kill the NV246, traditional ATF even quicker.