A couple months ago there was a discussion in one thread about Hamilton dials with the dial model/type number printed on the dial. I couldn't find it quickly so I will start a new thread. Here's a D 70 dial that is on a Ross I got recently. The dial is slightly concave and seems to match the illustration of the Ross in Rene Rondeau's book. The case is 14k gf with a 982 movement.

Yep, Hamilton's records show that dial "D-70" is indeed for the "Ross" model. Your dial is most certainly original since it bears the dial number.

The records I have show dial numbers for each dial from the mid-1920s through at least the late 1940s, including all of the grade 980 and 982 models. But I don't think the dial number appeared on every dial. It appears to that Hamilton did not begin placing the dial number on the dial until the late 1930s.

Bryan,
For those dials that had a dial number was the number always located at the bottom of the dial?