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That is the engine oil fill. Your transmission does not have a dipstick, it actually has to be pumped in through the drain plug hole. 6 qts need to be pumped in and then you start the engine. Let it run until the transmission heats up for about 5 minutes and then pull the plug. Let it drain until the stream of oil just starts to break apart. Put the drain plug back in and it the level should be fine. You need a pump like this http://www.ebay.com/itm/Ford-Transmission-Transfer-Case-Differential-Drive-Line-Fluid-Oil-Filler-Pump-/281085700242?hash=item4172036892&item=281085700242&vxp=mtr
To be exact, the transmission oil has to be 100 degrees F when you pull the plug. I found if you just let it run for a few minutes, you get right around the correct temperature.
Were you able to get the transmission pan filled again?