It looks like the oil pressure sensor is screwed into a right angle banjo fitting, but the leak seems to be coming from the crimp between the metal threads of the sensor and the plastic body.

 

https://www.dieselplace.com/forum/6...x-first-generation-2001-2004-lb7/968210-trying-replace-oil-pressure-sensor.html

https://lincolndieselspecialties.com/images/F143833812.png

97225635
SENSOR, Engine Oil Pressure/Temperature
SENSOR,ENGINE OIL PRESSURE GAGE(1.803) $39.02

 

Just replaced mine yesterday due to erratic needle movement. Fixed the problem.

You'll want from Amazon:
Lisle 13250 Oil Pressure Switch Socket - -$8
Standard Motor Products PS-230 Oil Pressure Switch - -$21 (non-prime item and took over a week to receive in the mail)

Remove yours (unclip wire first) and try some teflon tape on the threads to see if it stops leaking but it may be coming from the unit, not the threads. Get the Lisle socket and save yourself some grief.

 

Unplug it, probably leaking inside the connector. Just replaced mine and thats were it was leaking. Also the sensor just screws into the 90 degree fitting.