Kurt, thank you for uploading the spreadsheet; I will do my best to update it whenever I can (subject to new data points provided by members here). I guess a screenshot would allow others to see the data easily, so I can do that too. Obviously anyone else who wants to help can do updates too.
Perhaps to refresh the original question, maybe we could try and home in on further data points in the apparent gap in the (very limited) dates so far; it looks as though the stickers were introduced between 12B and some time around 02D. Maybe it's as simple as 01A, with a sticker Julian date code of '001'.
If anyone has an original wiper motor on a car assembled between 12B and 02D, that data would be very helpful!
As for the part number that Jim posted (5045608) I am kicking myself because I saw a car for sale on eBay that had the exact same number on it's wiper motor. I was in a hurry so I added the listing to my watched items for later, but somehow seem to have deleted it....... As far as I can recall, it wasn't a Chevrolet model, but a Pontiac - although of course it may not have been OE for that make or model.