4pcs Oxygen O2 Sensor 234-4012, 234-4018 Upstream and Downstream Sensor 1 and Sensor 2 for 1996-1998 chevy GMC C/F 1500 5.7L Code 4L60E COMPATIBLE WITH OEM NUMBERS: 234-4018,234-4012,13026,ES20000, SG272, 13474 2 Upstream oxygen sensor and 2 Downstream oxygen sensor for 96-98 chevy GMC C/F 1500 5.7L Code 4L60E Improved protection tube and increased thermal resistance prevents premature sensor failure and long warranty This is Brand New & High Quality Aftermarket Product service with Laser weld and Viton sealing system. Meet the professtional specification as OEM parts, for stable performance & durable Please check the description or use the year/make/model drop down bar and interchangeable part numbers to confirm the compatibility before purchase