My understanding was that anything over 8500 not both sides. Mine failed @ 6500 and my dealer did both sides! Possibly because of my 30yr history which them…… I don’t understand why a dealer would bring in a vehicle spend the time taking one side apart and then possibly six months down the road have to bring it back in and do the other side! Didn’t make sense to me or my dealer. Just demand it work with the dealer. Ask to speak with area rep.