That torque converter drain back can be an eye opener in the morning. I have a slight downhill grade on my driveway. If the truck is parked uphill, it will run back wards first thing in the morning. You must idle in gear or N to fill the converter, the pump does not work in Park, if I remember right. Crank it, put it in Neutral and give it 30 seconds, should pull right off. If not, you may have other problems.
Ronco