I posted a request for batch number info over on the AVA forum, to perhaps expand upon the numbers already submitted.
http://www.network54.com/Forum/40594...ol+enthusiasts......

Also, not sure if everyone is aware of it or not, but a point worthy of note in my post on the AVA:

As well, with some guns bearing a three digit batch number, you should remove the LHS grip to ensure that the batch number stamped into the front of the gun is not just the last three digits of a four digit batch number. For example, on one of my own Seniors, the front of the gun is stamped with "009" (which could also be misread as "600"), but upon removing the LHS grip, the batch number on the frame reads "1009".