Sir, my first Smith was a used 6-inch 629 that I traded into in 1988 or '89. I didn't know about dash numbers then, but I think it was probably a dash-1. I kept it only a short while before trading it off on something else. A couple years later, I bought a new 4-inch Model 25-9 that I still have.
Hope this helps, and Semper Fi.
Ron H.