the best way to change the fluid on the 4r70w is to pump as much as you can out the radiator cooler until it starts spitting air, then shut the car off.
Next drain the torque converter, it has a drainplug on it, you line up the motor with a breaker bar, turning it clockwise until you can see the drainplug.
Next put the plug back in the torque converter, and the rubber cap back on the bellhousing.
Then, you drop the pan, to find less than one quart of old fluid in the pan.
Throw that pan out, and get yourself a 98 deepsump pan with drainplug from ford, and get yourself a filter for a 96 transmission. Clean the magnet up with brake cleaner, and swap it over to the new pan. Swap over the pan gasket to the new pan, and torque all the pan bolts as per the manual.
Now is a good time to install a tranny cooler.
Then put six quarts of mercon v in the tranny, start it up, and shift the gears. Then put the rest of the fluid in there, and you are all set.
JH