Where is passenger side o2 sensor?

[lslincoln]

I have looked all over this forum for the location of the Bank 1 upstream? (1st o2 sensor) Can anyone tell me where it is. I have looked under the car and can very easily see the 2nd sensor. 2004 3.9L

 

[Quik LS]

it's in the standard O2 sensor location as in all cars - just before the cat. the second one is a cat efficiency monitor - and just after the cat.