This sounds a little nuts but if you look closely, the spacing and the alignment on the lettering is all over the place (not like the typically evenly spaced and clean stamping typical of Fabers). Also, every pic of a Faber tank I can find shows "FABER MADE IN ITALY"
Far from conclusive evidence on its own (styles and stamps change) but given the lack of other markings is highly suspicious. At the same time it's really hard to imagine someone going to all this trouble to fake up some tanks ..... and then not to finish the job with believable DOT markings. Very weird all around.