From the Holden VS Service Manual:
TRANSMISSION FLUID CHECKING PROCEDURE
1. Start engine and drive vehicle for a minimum of 24 km, or until transmission normal operating temperature is reached.
2. Park vehicle on level ground.
3. Move gear selector to 'PARK' position.
4. Apply park brake.
5. Let engine idle for 3 minutes with accessories turned off.
6. Locate the red coloured dipstick in the engine compartment, lift the locking lever, remove the dipstick and check fluid colour, condition and level.
7. If fluid level is low, add only enough DEXRON III to bring the level into the 'Hot' area.
NOTE: It is important to check the fluid level when the transmission has reached operating temperature. The 'Hot" range is calibrated to correspond to the correct fluid level for fluid between 82 and 94 C. If the vehicle is not at normal operating temperature, and the proper checking procedures are not followed, the result could be a false reading of the fluid level on the dipstick.
Important: Do not use any other than the recommended fluid in either a 1995 or 1996 Model Year transmission.
Inaccurate fluid level readings will result if checked immediately after the vehicle has been operated under any or all of the following conditions:
a. In high ambient temperatures above 32 C.
b. At sustained high speeds.
c. In heavy city traffic during hot weather.
d. Towing.
e. In commercial use (e.g. taxi).
If the vehicle has been operated under these conditions, switch the engine off and allow the vehicle to 'cool' for approximately thirty minutes. After the cool-down period, re-start the vehicle and continue from step 2, above.
Last time I did a trans fluid flush, the fluid came out of the top radiator outlet, so the flow is from the bottom to the top. Check the diagram in post #20 of the link below:
https://forums.justcommodores.com.au/threads/after-market-trans-cooler-pipes.278141/unread