Seen them a couple of times on engine, trans or the combination of the two donated to technical institutes, trade schools or even high schools in the 50-60's
Friend purchased a Hipo fairly recently from such a program - though it is unusual from what I've seen as most seem to not be high performance in nature typically
Years ago I purchase a bunch of stuff (Carbs, dists, fuel pumps, AC kits....) from a high school in the late 60's Some of the dist had etching on the exterior in code where the teacher had altered something in the unit for the students to discover and correct I guess. Lucky that that was only done on a couple of units. The rest just sat for decades in a closest at the school.
Couple of other labels/plates one might run across
Mercury Marine applications
Newer Industrial applications