[Patroller]

I wonder if there may have been an engine swap somewhere earlier in its life. According to the listing the Grizzly 450 should have a 421CC motor for 2009/10. A 2006 onwards Grizzly should have the 401CC motor. You can check here. https://www.autoevolution.com/moto/yamaha/grizzly/

 

[Patroller]

Maybe a plastic from another after damage.

 

[Patroller]

The VIN is usually located on the right side lower horizontal frame just behind the front tire. Right side when sitting on the ATV. however just learned that some models may have it on the left side for those sold in the UK or EU. See the link. Yamaha ATV & Quad Frame Number Location