Bosch 17014 Oxygen Sensor, OE Type Fitment

I just bought this from amazon. I did not say if it was for pre cath or post cath. Is there a way to figure out which one it goes too?
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2005 GLS 2.0 Liter
Lovin' it

 

I ordered this sensor as advertised for new, but a received what appeared to be used one shipped from some local user/seller. There was some kind of gray grease on the thread. The color of the nut and the body was brownish not stainless steel color.