something to look at is the return policy of these online stores. i can understand you have to pay shipping if you ordered the wrong part, but a manufactures defect should be free shipping back and the new part should be shipped to you for free. i can say i dont have experience with with other ones but i know rockauto sucks in this department. theyre a third party, i ordered a catalytic converter and the O2 bung was in the wrong location. it was the right part just assembled wrong, they wanted me to pay shipping all around then after i complained they offered to pay shipping one way then they stopped talking to me after a month or two i gave up.