3011 engine plug?

hello,

I have got a Zetor 3011 to restore. But there is a screw turned into the engine and i don't know what there has to be.
I made a couple of pictures so you know what i mean.
https://lh4.googleusercontent.com/-Ej4JWmPN98g/U2D2QCodG0I/AAAAAAAAApw/9eNxvAX5O9Y/w1598-h899-no/aanduiding+schroef.jpg
https://lh4.googleusercontent.com/-2ReEirnbEgg/U1uxRtDoSQI/AAAAAAAAAn8/fvMOnUHXHBU/w1598-h899-no/26.jpg

I hope you can help me out with this

Sander

Hi
There is suposed to be a oilpresure sviths or a pipe to the manometer in this hole depending on what your traktor hadd from faktory.
Bjarne

thank you.
I searched the web for the serial number of the oil pressure switch, but i can't find it. I can find it for a 3320 and 5011 and so on but not for the 3011.
Does anyone know what the product number is for this part?

Sander