Genuine Nissan Harmonic Bolt
Suits: GQ & GU RD28 Engines
Suits: GQ RB30 Engines
This is the Large Bolt that Tightens the front of the harmonic balancer and locks it to the crank.
If there is any damage to the bolt, you should replace it, don't risk your harmonic balancer coming loose or even worse, falling right off. Also make sure you have a washer fitted against the bolt head.