Look at that! They used to make styrofoam out of wood!
Lots of Starrett is still unchanged from generations ago. I've never seen any date codes...there are subtle differences in screw heads and such on the most modern versions. I think old catalogs may give clues because they note package type on some things, and on some old Starrett and B&S boxed items I have found such things as tiny date codes on the printed stuff with them, and once a 1936 calendar card issued by the company.
Are there Starrett and B&S freaks out there who are nuts about date clues, like Snap-on people??