Suit:
Nissan Navara D23 NP300 Thai built models with VIN# starting with MNT with the 2.3L Diesel Engine M9T
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.