If the model # is 572D it is the newest version for that perticular lens which came out in 2000.
I own the Tamron 70-300mm 4-5.6 1:2 macro (572D) and think it's a very good lens, however previous versions (i.e. 372D), are not rated as well. But on that same note, I have never used the previous models and don't know how they stack up to my 572D.
The one difference between the new and older versions, is that the new lens has a 1:2 macro and the previous, 1:4 macro.