I have been trying to find a correct box for you,, but so far,, I'm coming up empty. I have more boxes in my stuff,, I just can't "find" them right now.
But,, to answer your question.
Ruger didn't "date" boxes in the sense you mentioned. They had a few generic boxes,, that would fit a lot of guns, and they'd add the appropriate end label. The first boxes to have any dating type of info were the reddish-orange one piece, folding lid type. It had some patent data printed on the inside of the lid.
And they didn't believe in waste.
It wasn't until the yellow & black one piece hinged lid boxes came along that they did away with the pre-printed boxes. That was when having generic boxes were done,, and just the end labels were what designated what was in the boxes.
BUT,,, during that era,, there ARE some reddish-orange boxes with pasted on labels, and there are different colored boxes for a few models. Some of the earliest DA boxes were totally different than the normal production boxes. IF my memory is correct,,, the very early DA's had a white box, with a cut-out insert for the gun. Then they went to a red box with a black end on it.
But,,, again,,, if my memory is correct,, in 1981,, the box should have been a yellow & black 1 piece folding lid type.
For the DA guns,,, RoninPa needs to chime in,,, or Terry T needs to add his input. DA's are not my strong suit!