Ford manual on trans drain/fill. Measure what you take out. Do not fill past the fill plug. Skip the fancy Mytivac fill machine in the Ford manual. Use a long 3/16 hose and push in in to the fill port. Run it upward to a funnel. Put at least what you measured coming out back in to the trans. Then put some more until is runs out the fill port hole. Remove tube, put plug back. Next oil change, do it again and you should be pretty clean.
And with that, I'm outta here!
trans-drain-refill.pdf