Syltech combination sensor that provides oil temperature and pressure to two different terminals on the ECM. 4 wires -- the two just mentioned, 5V from the ECM, and a sensor ground wire.
I discovered this sensor by watching Tom on his YouTube channel - Ah Garage Time and his recent EFI build. The hard part was finding a M18 bushing with 1/8" female NPT threads, lol. A Subie specialist was able to obtain one from Killer B. Apparently Killer B is a Subie specialist shop as well based in Virginia. That took about 4 weeks to get this darn piece on the brown truck.