Jeff Stein
·It's a bit too late in the evening to work my way through all the responses, but this watch looks basically OK to me. It's the Reference 2406, with Landeron 13 movement. With the 454xx serial number on the case, the movement will not have either a serial number or any Heuer markings (ED Heuer or the shield). I might have expected to see the flat Heuer logo, rather than the later-style "deeper" shield, but they may have been transitioning around this time. Seems that the case has been polished; you will need much larger photos, or the Geiger counter and black light, to determine whether the lume on the dial and hands is original or has been refinished. It would be good to see the case-back, as these were either snap-back (earlier) or slotted / screw-back (later). I believe this one is slotted, but it's difficult to be certain.