3pcs O2 Sensor Upstream and Downstream Sensor 1 Sensor 2 Bank 1 Bank 2 for 1997 1998 Chevrolet Malibu V6 3.1L , 1999 Oldsmobile Cutlass V6 3.1L 2 Upstream + 1 Downstream Oxygen Sensor for 1997 1998 Chevrolet Malibu V6 3.1L Upper + Under Oxygen Sensor 1, 2 for 1999 Olds Cutlass 3.1L Package includes: 2 Upstream +1 Downstream Oxygen Sensor Warranty: 1 year umlimited miles. Please check the description or use the year/make/model drop down bar and interchangeable part numbers to confirm the compatibility before purchase.