Haha, glad you asked. Well they work at Guide Corporation here in Anderson which used to be owned by GM up until about 3 years ago. They made all headlights and taillights for GM vehicles. If you look at all original headlamps and taillamps on older GM cars and even some still today they will say "Guide" on them. Now they still make a lot of them but many are outsourced to other companies like Sylvania, etc. Guide also now makes lights for Ford, Daimler-Chrysler, etc, but back in the 70's it was all GM. My mom worked on the assembly line at the time (she's now in purchasing), and my Dad has been a machine builder there for 40 years so he has made or at least helped make the dies for all the lights they crank out.
Up until about 10 years ago they also made the entire front bumper assemblies for Corvettes.