Oreck_XL, that's interesting. Perhaps the Cadillac vacs were offered with a new car, I've heard that many times. However, I will tell you that Clements kept using the Cadillac name, point in fact, they STILL use it. Before they got bought out, their website very loudly proclaimed that they trademarked the name 'Cadillac' in like 1914 or thereabouts. Plus they sold their vacs through (vacuum) dealers for about as long as they made vacs, and advertised them in magazines, etc. So maybe they did get paired with cars, but they didn't treat the brand name as something especially for pairing with cars.
They also made a tank cleaner for Admiral at some point.
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Jeff, that sure is the exact same Eureka. The nozzle latch must be a common problem. The broken piece on yours, is it aluminum? My guess, without ever having seen one, is that it would be a thin piece of aluminum, meant to be a rotating latch.