The Saab spec is Dexron II ATF. Not sure if there is a synthetic equivalent. The right type of oil is very important in autoboxes!
Fluid capacity is 8.4 litres including torque converter and oil cooler. Manual states that only 3.3 litres can be drained via the oil filter (subject to removal!). So if changing brand of oil make sure all existing 8.4 litres is out or you could mix different types.
Stick with Dexron unless you get a specialist approval of another type of oil!
Of course, to check auto box level engine must be running, at normal running temp, and selector should be in 'Park' position.
From what I have found out it is not worth changing the brand of oil in the auto box. Any specialist I have spoken to all say use only Dexron. I had a problem with my autobox and when I drained it the colour and smell of some of the oil led me to believe it had been topped up with the wrong oil, so I would recommend only Dexron III as it is now(replaces Dexron II)