These are both Factory along with ones that appear factory and some that are not. ALL sensors get checked to be a working sensor on my engine test stand, so piece of mind that the sensor you purchase is in working condition unlike cheaper made new products you purchase now days. The factory ones have the part number on them, the others look and feel just like factory without a number. Others are aftermarket but come off a running driving vehicle so should be good useable condition!
Will be adding 5.2/5.9 V8 ones soon, when I can test them!
