Sinn 903 ST - about to buy a gen. Are there any fakes out there I should worry about?

[Lifting]

I have found a used 903 ST on another site, hopefully a gen, but you never know. It is always a bit difficult to verify from a website, and I know the old phrase "buy the seller" is always ringing in my mind. The seller seems genuine, but he is not the original owner, so it is always possible that he has been duped. Anyway the question really is, has anyone seen any fake 903's around and if so are there any really obvious telltale signs to watch out for. Many thanks in advance.