I just replaced mine. Got em from needswing and it took me a hour and a half. I used 3/8 torque wrench 3/8 drive ratchet 3 in extension and a universal and a spark plug socket. It wasnt that hard at all actually quite easy. I replaced em at 5 yrs 63,000 they looked ok, could of went longer on em but I just follow what is says in the book for insurance.....5 yrs or 100k miles