Thanks to Randy Hedeen, we now have a great guide to identify when cartridge boxes from Peters were manufactured!
This sample provides a rough idea of when a box was made, and is not intended to be a comprehensive list of every variation made.
Can someone provide similar info for some of the other major makers? PM me for an address to send some .jpg images and some text and I will convert it into web format for you.
Again, a BIG thank you to Randy for his sharing this info!