Is there a problem with the trans or is this just routine maintenance? In either case, I would advise only draining and removing the pan, changing the filter, checking the oil tubes (especially the one to the differential), and refilling. Flushing is risky with a trans that has higher mileage and all but unnecessary with a trans that has been regularly service, regardless of mileage.
If you are contemplating a flush due to apparent problems, that could be the worst option. It would be far better to install a drain plug in the pan and change the fluid and filter more frequently to clean up the trans.