oxygen sensors

Can someone tell me where the bank 1 O2 sensor is on a 2000 silverado 1500 5.3 litre with dual cats? There is one before the cat and one after the cat on each side. Have tried other forums with no luck. ty Terry

Bank 1 is the left (drivers) side

I need to know where the oxygen sensor is located on a 2002 Silverado myself. I had it diagnosed a couple of months back as a knock sensor. Took to the dealer and was told that my fuel injectors just needed to be cleaned. Not even a month later Check Engine light is back on. Took to Autozone for diagnosis and was told to replace the oxygen sensor. Any help is very much appreciated!