You might have an
oil pressure sending unit there. I think it is a 3/8" US Pipe thread. Really helps with
oil distribution within the engine. If it is plugged, remove hte plug, but watchout,
oil really flows out.
Oil filter is on the left side of the block. The port is back from that and up just a hair. On the four bolt main blocks I have worked on, it is usually used for the oil pressure sending unit on select cars.
Rick, if you are following this thread; what do/did you connect to the port next to the oil filter connection?
