There's a document on the internet that has some valuable information to date older ballasts, especially those used during the PCB era in the Canadian market.

Here's a couple of examples:

Canadian General Electric:
Four digit number either printed on the ballast label or stamped on the back of the case, reverse the first two digits. Then it becomes a date in the format YYMM.
Example: 2811 - November 1982.

GE USA:
Two Letter Code stamped on the flange. Use this document to decode the date.
Document no longer available, see following post by Eric for a copy of the GE date code chart.

you will find this relevant

https://www.lighting-gallery.net/index.php?topic=10760.msg88165#msg88165

I wonder if this applies to Canadian made GE lamps as well.

For lamps, try looking at the various date code charts James has setup on his webpage here.

@ Joseph - The link to the PDF in your original message for the 2-letter codes isn't working. It just goes to the main page of their site, not to a PDF.

@Rommie - Unfortunately, it's not working because anything that's not LED got wiped off the site, and updated with only LED.

'twas ever thus 

Oh I changed my username a little while ago 

Oops, didn't realize that. My bad.

Yeah I guess GE must have wiped that ballast PDF from their website. Anyway the chart looked identical to the one posted by Eric. I might have a saved copy of that PDF saved somewhere too. If I find it I'll update the link for it.

 I suspected this happens when GE it self unloaded there lighting divison,   Taking down orginal GE site as Servant took over.   But ballast must state no PCBs after the PCBs
 Bans.