Hi Evan - it’s lovely to see your original Heuer Autavia 45 reference 3646 H. This is the second Autavia case with screw back and the third dial variation with straight steel hands. You can find this watch in the Chronosport catalogue page 20 in the catalogue section of this site. These are slightly smaller than the later snap back case and in my opinion very elegant. Heuer also made the 12-hour version, which has the three sub register. These are my two that I wear on a regular basis and now that I have them I have no need for a Rolex Daytona. regards Paul