Oil pressure sensor location?

[300sdToronto]

I'd be very grateful if someone could tell me where the oil pressure sensor is on my 1983 300sd ...... I was poking around tonight, admittedly with a rather dim light in freezing temps, and could not see anything that looked right.

I have the classic symptom of failure - gauge at 3 bar when the ignition goes on, but without the engine running!

Thank you.