There were several minor changes made to the NID during its 20+ years of production. One example would be the stars you see on a lot of NID's. Some people refer to them as "star grade" guns, but that was just one version. The snail's ears lasted, I believe, right up until the final version--on which the Field Grade engraving was a simple line around the border, the cocking indicators went away, and the top of the receiver was stippled. It was probably the simplest design, but it's the one I've always preferred. Cleaner-looking, to me, than earlier versions.
