That one is a 3-brush unit that would have been used on 1930s or early 40s vehicles. Also some farm machinery into the 1950s. The square item on top is a cutout relay. If someone is doing a "numbers-correct" restoration job on a very early car or truck, that would be the only reason to try to use it.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!