When you need to change or upgrade your Harmonic Balancer
2 Hardened Washers
1 Hardened M16-2.0 Threaded Rod
This Tool works on LSX base Engines in Trans Am, Firebird, Camaro, Corvette, GTO, Grand Prix, Bonneville, Trail Blazer, Envoy and ALL LQ4 LQ9 4.8, 5.3, 6.0 Liter GM Silverado GMC Sierra Truck Engines, and L92 style LS3 LS7 LS9 Engines. I recommend purchasing a new Harmonic Balancer Bolt with this tool.