This is why newer trucks don't have an ATF stick--people don't know how to read them. I do not know what your manual says, but I would follow it. My ZF has a drain and fill hole on it. First, let me just say, that ATF fluid is very expansive with heat. Hot fluid reads a lot higher. With my truck, I have a fill hole, no dipstick. You fill it, you start the truck cold, you continue to fill it till it spills out the hole, then you plug the hole as fast as you can.
With previous trucks, with dipsticks, you start the truck cold, shift through the gears, put in neutral, check the level and fill accordingly. Hot fluid readings are false. Non-running readings are false. There is plenty on the net to explain why.