Rebuilt Harmonic Damper fits 330-425 Oldsmobile engine. Replace your cracked and dried out rubber dampening ring balancer with a rebuilt factory unit. Old rubber ring is cooked out. Balancer is shot blasted for stress relief and cleaning and then reassembled injecting silicone rubber and heat curing. Tests show balancer to be three times stronger than stock. Recommended over 350 horsepower. Core deposit included in price. Send in a core and get a $30.00 credit or I can do your old one. No high performance engine should be without one. Also available for any engine any make with two piece rubber damping ring balancer.