I defer to someone who knows the punches better than I do. I don't know if this is just a case where there are typically two levels of detail or this is atypical. It looks like two levels surrounding the letters rather than to one side.
It is O-102. When first looking I was hoping for O-101, a strong R-5+ which used the same reverse die.
@micbraun and @okbustchaser, you beat me to the punch. Thank you for looking into the attribution for me.
I picked this up today at the Post Office. It must be attributed to be fully appreciated. It joins it's sisters: