It could be from a few different areas honestly...could be coming out of the primary around the 2 bolts that hold the tension shoe bracket....those 2 bolts go thru the back side of the primary...it also can be a primary housing gasket leaking itself...it also could be coming from the oring between the inner primary and the transmission...it could also be something on the transmission...only way to find out is to clean the area really good and ride it a little to see if you can tell where the leak begins