You'll see two hard lines attached to the frame rail. The line on the left is the return line from the pressure regulator. The hard line on the right is the inlet coming from the pump running to the filter and on to the dampener/fuel rail.
If it's still oem, you'll see an oem squeeze-type clamp on the return line as this is a low pressure line. The inlet will have a screw-type fuel line clamp on it.