Where is the oxygen sensor located on my 1997 Dodge Grand Caravan, 3 liter V6?

Hello,

There are three oxygen sensors for this vehicle.
One in each exhaust manifold and one after the catalytic converter.

https://www.2carpros.com/articles/how-an-oxygen-sensor-works
https://www.2carpros.com/articles/how-to-test-an-oxygen-sensor-02-sensor
https://www.2carpros.com/articles/how-to-replace-an-oxygen-sensor

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.