All supercharged LS type engines MUST have the crankshaft and balancer either "keyed" or "pnned"together. The harmonic balancer will spin on the crankshaft and cause damage to the crankshaft and balancer if this is not done. Some aftermarket crankshafts and harmonic balancers come with keyways machined in them from the factory. OE crankshafts and harmonic balancers do not. Keying the crankshaft is only possible with the engine and crankshaft removed. The A&A Crankshaft Pinning Kit allows the crankshaft and harmonic balancer to be locked together with a hardened steel pin without removing the harmonic balancer or crankshaft. A fixture is provided to guide a ¼? drill bit into exactly the right spot. Once the hole is drilled, the pin is inserted and the provided OE harmonic balancer bolt is inserted and tightened. Includes steel drilling fixture, hardened locking pin, 16MM fixture bolt and new factory balancer bolt. This pinning kit is included in our supercharger systems.