[mustang67408]

On a V-8 Bank 1 is the drivers side (LEFT)
On a V-6 Bank 1 is the passenger side (RIGHT)

02 sensors = The oxygen sensor is a measuring probe for determining the amount of oxygen in the exhaust; actually they are mounted inside of your exhaust pipe. Oxygen sensors does their job by continually monitoring exhaust gases and signals the engine computer to adjust the air/fuel ratio to make sure that gasoline combustion is as complete as possible, thus reducing harmful emissions while also improving engine performance and fuel efficiency.
If the mixture is too rich or too lean, the oxygen sensor adjusts the amount of fuel that enters your engine accordingly. The wrong mix of gasoline and oxygen can increase pollutants that exit your vehicle – thereby harming the environment. And not only that, it is also one of the causes of faulty catalytic converter and engine damage. Therefore, a properly working oxygen sensor is a must for every car. But like any other car parts, oxygen sensors don’t last forever. The normal aging process will eventually cause the oxygen sensor to stop working.

I get all my parts from a Toyota deaership, they cost as much or LESS than the aftermarket stuff. Pm me for details