My 2001 Denali Awd Issues

[KillerMike]

Well this is my first post on this forum but after reading alot of usefull post's etc... I decided to sign up. Anyways, I have a 2001 GMC Denali with 75k. Its tastefully done with a shaved tailgate/rollpan, 23's on 315 toyo's, Baer big-brake kit, blah blah blah you've seen it all. Anyways, my real question here is that im having some issues with the AWD. It makes a good amount of whining noise when at low RPM's and it gets to the point where i have to turn the friggen radio up or get off the throttle to get it out of my head. If im on the highway for long periods of time, when i get off after say an hour or so of driving, I will go to make a somewhat of a sharp turn and it seems as though my front wheels are skipping. Almost as if my rims where rubbing REAL bad. But thats not the case as now into winter I have plain 20's on. Im 100% sure its NOT the wheels rubbing. I worked at a chevy dealership recently and I was close with a tech who told me that i needed to change the Autotrac transfercase fluid. Run it for a couple days, drain and re-fill to be perfect. So as of right now, i just changed the fluid with the GM autotrac fliud 3 or 4 days ago. Im going to go get a couple more bottles and drain/refill it again. After I changed the fliud for the first time (4 days ago) I thought I might see a little improvment in whining noise etc... but no. Allthough i am going to drain and refill it again, it still sounds like sh*t. Even worse, 2 nights ago i went for about a 2 hour round trip ride, got off the highway by my house and pulled into a store, as i slow down and turn into the store, as the wheel turns my front wheel and WHOLE front-end where going CLUNK CLUNK CLUNK and snapping. It did this once before after a long highway ride thats why i new it was after long rides. But once i get home, i come out the next morning, and its not even CLOSE to what it was doing last night. Its almost as if the transfercase (whole AWD system) gets real hot after driving for a while and Binds up. Im kind of at a dead end after changing the fluid so basically im wondering if anyone has been through this. Sorry for the long post but ANY help is appriciated. Thanks guys.