Bank one is the side of the engine with cylinder number one. Bank two would be the other side if equipped. Sensor one is before the catalytic converter, sensor two is after.
All O2 sensors are located in the exhaust system at various points.
Pre or Post?
YES
You have several O2 sensors on that vehicle and they are all threaded into the exhaust system at various points.
Diesels do not use oxygen sensors
All O2 sensors are threaded into the exhaust system at various points. Upstream O2 sensors are located before the catalytic converter(s) and downstream O2 sensors are located after the catalytic converter(s).
There are four o2 sensors on a montero sport.
The 1998 Taurus 3.0 has four o2 sensors. There is one in each exhaust manifold, one in the exhaust just in front of the catalytic converter, and one behind the converter.
All O2 sensors are located somewhere on the exhaust system.
1996 and later gasoline engines are equipped with pre and post catalyst O2 sensors. The sensors are located in the exhaust mainfold one before the catalytic converter and one after.
The 2.5 has 2 O2 sensors (both on top of the engine) and the 3.5 has 4 O2 sensors (two on top, and two under the car).
The o2 sensors screw in. There is a special socket for removing the 02 sensors with a slot in the side to clear the wiring.