Came across this information on GM MP Transfer Cases:

2008-09 GM Transfer Cases RPO NQG, 1222,1225,1226, RPO NQF 1625,1626, RPO NQH 3023,3024

Starting with the 2008 model year General Motors introduced a series of new transfer case designs to replace the New Venture Gear designed transfer cases used for many years. Built by a company known as Magna Powertrain (MP) the new design units are available as 3 different models:

Manual Shift ( RPO NQG) (Models 1222/1225/1226)
Electric Shift (RPO NQF) (Models 1625/1626)
Auto (RPO NQH) (Models 3023/3024)

Several models are available for each application, these include the 1222/1225 and 1226 manually shifted units, the 1625/1626 electric shift units and the 3023 and 3024 auto/active transfer case model.

Note: All models use Dexron VI fluid.

It's interesting to note that all the transfer cases, whether manual, electric, or auto all use Dexron VI fluid.

I checked the owner's manual for my 2008 3/4 ton Suburban with the MP Auto transfer case, Model 3024 and sure enough, it calls for Dexron VI. This is a vehicle that has Autotrak 4 wheel drive. However, I contacted two GM dealers in two separate cities and they claimed, using my vehicle's VIN, that I should be using Auto Track II. I have not yet seen any service Bulletin that claims that a change to Autotrak II from Dextron VI was approved. If someone has seen it, please post the details.

SD