There are no shipping records available on Henry rifles, other than approximate year of manufacture, which you already have. If this rifle was made in 1866, it is near the end of production for the Henry. Without the serail number, it would be difficult to pin point. I am surprised that the savage99 site would have the correct info. The engraving is definately a Hoggson pattern and appears to be original, but without close-up photos or examining the gun face to face, one can only speculate. There is a familiar saying among collectors, that there are far more "factory" engraved Henry's today, than ever left the factory. In other words, many fakers as far back as the 1950's were having standard Henry rifles engraved in the traditional factory patterns and passing them off as original. In doing so, many extraordinary standard grade Henry rifles were totally destroyed, value wise. In some cases, it takes a very trained eye and someone who has more than just a general knowledge of the Henry, to determine the originallity of the engraving.