Vintage Cars: oxygen sensor, electronic fuel injector, lambda sensors

Question
i have a 1979 mercedes-benz 280 e and was looking at my car manuals to find the location of oxygen sensor and had no luck . does it have a oxygen sensor and can you please tell me where it is and how to remove it.

Answer
let me do a little research , you may or may not have one this was a transition year, technically you should have a Kjet system without lambda ( O2 sensor)
MB started using lambda sensors in the  80's

If it had one it  would be around catalytic convertor

I dont know why  I did not catch this before. I will be back to you

OK this is why I am confused
SOME california models had them as early as 79, most US versions started in 80 -81
The main  feature of the system is the frequency valve which looks like an electronic fuel injector in the control circuit of the fuel distributor.
hope this helps