Check engine light is indicating I need a new "back" or "rear" O2 sensor. I am unable to determine what part # this refers to. Also am unclear as to the location of the sensor. Have determined from other posts that if I lift the passenger carpet I can find what I believe to be the connection for the electric, but I am uncertain as to which sensor this goes to.

Any help, guidance, etc would be appreciated. My skills run to the brakes, belts, alternator level, but this would be first DIY repair on the MB. I am just reluctant to give away 250$ on what I gather from other threads to be a "5 minute repair"

Also, does the Mustang 302 O2 Sensor trick apply to this repair?