[Kevin 1G Drummer]

The port on the bottom of the turbo is the oil drain which goes to the oil pan, the port on the front of the turbo is the coolant return, the port on the top is the oil feed which comes from either the head or the oil pump housing depending on your setup, and the port on the back of the turbo is the coolant feed which comes from the water pipe that goes across the front of the block.