I stumbled upon some vintage images showing the various production areas at the Sylvania Drummondville plant. They seen to be from the 1970s or the 1980s based on the products I see being manufactured in the pictures. There's a few shots showing the mercury lamp production too, from the arctube filling, to frame assembly, to sealing of the final lamp.
Sylvania Drummondville(Yes, I know it's on Facebook but you don't have to log in to view the pictures, Just open the link in a private session)