Kwiksen 2pcs Heated Upstream and Downstream Oxygen O2 Sensor 234-4112 234-4285 for 2002 2003 Chevrolet Trailblazer Trailblazer EXT 4.2L/GMC Envoy Envoy XL 4.2L/Oldsmobile Bravada PART NUMBER: 234-4112 x1, 234-4285 x1 O2 Sensor 1 and Sensor 2 for 2002 2003 GMC Envoy Envoy XL 4.2L Upper & Under O2 Sensor for 2002 2003 Chevrolet Trailblazer Trailblazer EXT 4.2L Length 234-4112: 450 mm, 234-4285: 425 mm Please check the description or use the year/make/model drop down bar and interchangeable part numbers to confirm the compatibility before purchase