never use an aluminum crank pulley. they can force the crank bollt out. the only way i would use an aluminum pulley is if i had the time and patience to retorque it as often as possible. a car at the track threw the crank pulley bolt thru station 14 where there were 2 corner workers inside. then the crank pulley got sloppy and trashed the crank and the pulley. moral of story, aluminum crank pulleys can kill someone.