Terry, thanks for sharing what you have, looks so far like you're the Lone Ranger. So it appears based on the pic's you posted that by 1973 the date wheel was gone and perhaps there was a different case manufacturer, or multiple case manufacturers? So many questions remain and with scarcity of original batteries the sample size and conclusive findings may be difficult.

Hopefully one day someone can add to the stamping on the top of the post . . .