Can anyone tell me what these senders are please?

The double one is at the back of the block


The single one is on the dipstick side of the engine


I guess its connected to the fault with my oil guage which does not work at all


Just need to know what to but and where to put it !

Hop you guys can help?

 

The first picture shows two oil pressure sensors.
On our Chevy's the sensor uses a single wire, these might be aftermarket units.

The second one is your knock sensor. Connects to a single wire as well.

 

the oil pressure sensors shown are just on/off pressure switches-no wonder the oil pressure gauge doesn't work.The single terminal one probably meant for warning light,the dual terminal one likely for fuel pump turn-on-(in factory setup,actually the "failsafe"to complete circuit to fuel pump if the fuel pump relay fails)

 

Great ! Thanks guys
I'll just put the oil light in the new engine for now and get a pressure guage later