It appears to be the heat exchange above the starter. I don't know what the correct term is for it. It is the rectangular box with both coolant and atf lines. There doesn't seem to be any cross contamination but atf drops are forming on the bottom of the starter. Is this a common issue. How difficult is it to replace the box or gasket.

 

Upon glancing at the Shop manual it is a heat exchange. Is there anything inside of this thing that can leak or is it more likely the fitting from the atf line.