PlayboyPenguin, it's not easy to be able to know what's up with the Taurus product line because Taurus marketing/sales info is either 3 steps ahead or behind of their product line. They also really need to just rename each revision of the Millennium series, IMO.
Safe to say, right now you have 3 options on the market regarding the Millennuim series:
Gen 1 DAO Millenniums (AKA the "frame cracking" generation).
Slide says "Millennium" on one side, "PT-(model number)" on other.
Gen 2 DAO Millennium PROs (Smoothed out DAO trigger, and no cracking problems- what the Millennium should have been to begin with. It's what I currently have, and it's been great and reliable for me).
Slide says "Millennium PRO" on one side, "PT-(model number)" on other.
Gen 3 "SA/DA" Millennium PROs (Single action trigger with second-strike capability on FTF, Heinie straight-eight sights... this is what's now coming out of the factory, and I have one coming).
Slide says "Millennium" on one side, "PT-(model number)
PRO" on other.
You can still get the older versions used and NIB as well if you look around online.
...Whew!
Don't know if you actually want the info, but there it is anyway.