I don't have one to be able to compare, but the only fakes I've seen online have the shoulder joints the wrong way around.
So this looks real... plus a tatty old box makes it seem likely to be real too

You're safe. That piece is authentic.

All the packaging and the number plate are exactly how they should be.

On the pieces assumed to be fakes, the screws used to put it together have flat heads. Where as on the authentic pieces, they're bubbled, with a weird slope. If you look at the close-ups in the photos, you can see what I mean. They're somewhat of a unique screw head.

Unfortunately, seller did not purchased directly from Kawsone, and the retailer did not provide the outer shipping box to him, which bears the serial number. 

Its authentic as stated in earlier post by another member these have unique screw's and they are of a certaon weight and built with tge utmost quality ive seen and handled a fake and they sre lighter and there are small nuances that make it noticeable so this piece is authentic i compared it to mine and its all correct.

Buy with confidance although it does sewm to have some serious surface scratches and abrasions so you might want to take xuation with polishing it becuase under a display setting with lights the scratches will jump out like a sore thumb.

I've spent hours studying these. I own the black chrome, from reputable toy shop with outter box and cleaning cloth.

I would say this is 75% fake. I will not give exact details on why I think so because i don't want that info out there for bootlegers to fix their issues.

The flat head screws have been switched out of the fakes so that is no longer the tell tale sign. But there are other minute, tiny differences.

I've learned the hard way.... Especially with kaws figures... If you're every unsure or have a bad feeling stay clear.