Land Rover Repair: 97 discovery oxygen sensor, o2 sensors, landrover discovery

Question
G'day John,
I bought a '97 3.9l V8 landrover discovery (big mistake, but it does sound nice) because it had been converted to LPG.
It seems to be running too rich as I only get about 4.5 km per litre of gas (12.5 mpg) and the exhaust smells rich.
I don't use it on petrol so I don't know the mileage on petrol.
I have been looking for the O2 sensors which the manual says are located before the cataclysmic converter but I have searched the entire exhaust system and can't find anything with wires anywhere on the exhaust, from the manifold to the tailpipe.
Soooo,  my question iiis,,,, where the .... are the O2 sensors on a '97 3.9l V8 Discovery??

Thanks
Peter S.

Answer
On a normal 1997 V8 Land Rover there are 4 o2 sensors, two in front of each catalyst, and too in back.  They screw into the catalysts.

It's possible you have a truck that does not have catalysts or o2 sensors.  I know LR sells them like that in some countries, but not here in America where I am.