NEW DEXRON ATF in Transfer Case?

The dealer that I use told me that they only have one ATF fluid now, the new Dex VI. or is it V ?
They were under the impression that they should use all trac fluid for refills on the transfer cases, but aren't the 2500/3500 trucks supposed to use Dexron III in the t/cases? If so then I guess the new Dex fluid is the ticket?
I was under the impression that the trans got the Dex VI and the cases still got the older Dex III from the factory. Any one know for sure?

Starting in model year 2006, Dexron VI was introduced to meet the needs of the new 6 speed 6L80 and similar transmissions. It was backward compatible with automatic transmissions using Dexron versions of the past. It is NOT supposed to be used in anything else that originally used Dexron III, such as t/cases and manual transmissions. I believe that you can still use Dex III in non autotrac, i.e. manual or electric shift transfer cases, however, GM lists the following for your truck - Manual Transmission Fluid GM Part # 88861800.
Autotrac fluid has never been recommended for a manual or electric shift t/case found in HD trucks.

This bulletin spells it out. 04-07-30-037C Any vehicle that previously required DEXRON®-III for a manual transmission or transfer case should now use P/N 88861800. This fluid is labeled Manual Transmission and Transfer Case Fluid.

Thanks, I'll let my dealer know. I thought there was a difference. It is confusing to say the least. I know there have been people that used Transynd in there transfer cases. I always thought that is was better than Dexron III but maybe not in the t/cases. There are some that are running 05w30w synthetic motor oil in the transfer cases. They claim it lubes better and handles the heat better. I'll go with what GM say's since it is under warranty.
I have been having a seal leak at the rear output shaft on our t/case at the driveshaft yoke. If you have time maybe you could read my post on the trucks and drivetrain section.
I would be greatful for any idea's as to why this leak is reoccurring imeadiatley after a new yoke and seal were installed.

A few of my vehicles have had leaking transfer case parts and its a pain to find good salvage units. any one got any suggestions other than salvage yards?