I want to say the 1981 pipes without the x/1000 numbers were seconds from that original runThis is absolutely bizarre. My guess is that the earliest ones came with the large stamp but the decision makers thought it was too bold, created the smaller stamp, then all subsequent stamps had the smaller one.
Did the 1981 hallmarks predate the serialized series that were x/1000?
I’m going to tag my usual references to chime in in case they know @ashdigger @RustiePyles CPG