Chrysler Aspen Transmission/Transfer case question

For you Durango and Aspen owners, I have a question about changing the fluid in the transmission/transfer case. It is AWD and I am wondering if the transfer case is an integral part of the transmission and requires no drain/refill as changing the tranny fluid changes both. Or, do I have to drain and refill the transfer case as well as the tranny. This is a 2008 Aspen and as I mentioned it is AWD. Have only had it about 5 days and want to change all of the fluids in it. So far, I love this vehicle. Will be hauling grandchildren and a camper. Looking forward to a lot of fun!!! Thanks for your help…..