This one has been around for a long time, so there are a few different versions available. I have the tall ridged bottle EDT made in the USA as well as the one made in the UK and their corresponding aftershaves. (and there is at least one older version in different bottle and packaging)
The only difference I can perceive between the two versions I own is that in the top notes in the older made in USA version smells something like a bitter floral liqueur, while the newer UK version smells harsher and "greener" to me. But this is really only for the first five minutes, the drydowns of both are identical to my nose and both outrageously good.
The version in the new packaging I don't own yet, but I tested it once and it seemed sound to me...I'll buy it eventually when I start getting low on the older stuff.
I'm just so grateful that Aramis continues to make 900. It must be a good seller for them to have re-introduced it as part of the Gentleman's Collection, and I'm glad for it because it's my number one favorite fragrance and one of those rare older classics that, I feel, has remained true.