ok sorry, im not trying to bash ya.
but if you know the car has been taken care of and regular maintance has been done to the transmission, then a flush should be ok. But if the fluid has not been changed in a super long time and flush can destory it, it may dis-lodge debris in the line and cause the trans to fail.
Here is a good vid to help ya understand how to change the supercharger oil, if you wanna do it yourself, its easy, but kinda smelly. Im just trying to save ya some money.
YouTube - HOW TO CHANGE THE SUPERCHARGER OIL ON A GM 3800 SERIES II V6
