^how will i know which bolts to line up?It could be 'slightly off' and you may not even realize it.
But its ok just as long as your not terrbily off, and if you were you would notice it.
You see the pulley is connected to a Vibration damper. YOu want to mark the bolts and reasemble it as close as you can to the balanced damper. The pulley and damper are initally balanced as a unit so if you unbolt it and slap it on with out a care in the world it may not be balanced correctly to the damper