As you should be able to locate from the pictures in Ken Lunde's wonderful FAQ, walther uses standard two-letter date codes. A=0, B=1. They skip J, so 9=K. KI=1998, AB=2001, etc.
You can quickly tell if it's really new or not-so-new because in early to mid-2004 they removed the so-called "ski jump ramp" from the inside of the trigger guard, and if I recall they also went to standard rails.