How many 02 sensor on a 1996 1500 Chevy 4x4 pickup truck and where are they located?

A 1996 Chevy 1500 4x4 pickup truck typically has two O2 sensors: one located in the exhaust manifold before the catalytic converter (upstream sensor) and another located after the catalytic converter (downstream sensor). The upstream sensor monitors the air-fuel mixture, while the downstream sensor checks the efficiency of the catalytic converter. These sensors are essential for the vehicle's emission control system.