I'd like to find a 1948 (birth year) super speed with case, but it appears that there is no easy way to differentiate 1947 from 1948 from 1949 with these razors (except that 1947-48 ones came in a cardboard box). Does anyone know a way to do that, to make sure that what I'm getting - when I make an offer here or elsewhere - is really a 1948? Thanks.