Bad assumption. Code may mean the O2 is working correctly and the truck is simply running rich or lean. AFAIK no code definitively says that the O2 sensor is the sole culprit.
It is an item that fails of course, if it's original it's not going to hurt anything if you change it, assuming the replacement is good. Suggest AC Delco replacement only.
Edit:by no means am I saying it can't be bad. Only that the system has no way of testing the sensor...the ecm simply expects a certain response under certain conditions, and if it doesn't see that throws a code. If the system was self sensor diagnosing, you wouldn't have multiple codes as a possibility.
I broke an intake valve stud, got a rich O2 code...because the runner filled with fuel and flooded the other cylinders, which the ECM couldn't adjust for, leading to rich exhaust, not a bad O2 sensor.