As someone else has said, call them and ask for the serial numbers of the lenses they have in stock. They should get back to you in 24-48 hours.
As far as KEH rating is concerned, most believe that their rating is conservative; I do as well, with a caveat -- I think the conservative rating, e.g., a like-new lens rated as BGN, is directly related to the quantity of that lens that KEH has in its inventory.
So, something of which they have 10 or 20 in inventory may get a BGN rating, while something of which they only have 2-3 may get an EX or EX+ rating, even if all of those lenses are very, very clean.
Of course, BGN could also be a "user."
Just my $0.02
Keith