The NOS full quarters that I have are metal date stamped and the repos I have had in the past were not.
That is usually what I check for, if I dont have my mics with me.
The part sticker isn't a certain thing either. A few years ago there was a guy selling the stickers and boxes, after someone would buy the OEM panels from him.
I can't remember his name, but he had a huge ad in Hemmings.