...This is the oil pressure port that supplies oil to the BOSCH MFI injection pump via the oil line. The oil pressure sending unit that feeds the gauge on the dash screws into the side of this fitting.
Usually, you can't get a clear view of this part because the crank case breather hose is blocking it. Attached is a photo to show you where it is located, look here https://pbase.com/image/73330316
Thank you Bernie!