How many batteries does it take? If it take six batteries it is the 2003 model, If it takes 3 batteries, then it's the 2007 model.
Is there a lever on the clamp? If there is it is ANH model if there isn't any, it's ESB.
The biggest difference between the 2003 ANH and 2007 ANH model is the size. The 2007 version is shorter by an inch and pretty much the same scale as a real MPP.