The 370Z Nismos are no longer individually numbered. That happened a couple years ago when they expanded the Nismo edition to models other than the 370Z.
The VIN will tell you whether it is a legit Nismo. Or a knowledgeable individual could probably tell you with a careful inspection.
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2011 370Z 6MT Sport Gun Metallic | ARC | CJM | Ecutek | FI | Fujimura | R2C | SPL | Stillen | TWM | Z1 | ZSpeed | |