The substantially stiffer emissions requirements for diesels went into effect for engines produced after 1/1/07. The next significant stiffer level was 1/1/2010. Note, this is the engine build date, and many chassis makers bought well ahead. So, it is possible to find a 2008 or perhaps even a 2009 (and 2010 and 2011 for the 2010 engines) that does not meet (or need to meet) these standards.
And, as Scott said, not all engine manufacturers used the same techniques for meeting the standards. Indeed even within a particular manufacturer not all engine necessarily used the same techniques for meeting the standards.