I tried to search the forum for info on Auto Trak II but couldn't find much. Since about 2007 or 08, GM has been using transfer cases build by Magna Powertrain. Two of the models are Auto Transfer cases, in other words, they have an Auto setting that allows the 4WD system to sense wheel slippage and apply the internal clutches to engage the system. The two are MP 3023 and MP 3024. The owners manuals for all the GM trucks since 2008 call for Dexron 6 for the transfer cases and a service interval of 45,000 to 50,000 miles for severe duty. I got in touch with two GM dealers from two different cities to confirm that I should be using Dexron 6 for the MP3024 transfer case but both told me I should be using Auto Trak II because its an "Auto" transfer case. The owners manual does not reflect this. Has anyone else seen this advice from the GM dealer? Please keep this discussion to just Auto Trak II vs Dexron 6. I know there is other advice out there for other fluids, but I just want to clarify the advice that's coming from GM. Thanks.