I have seen this too. I bought one at the flea market about 7 or 8 years ago. It was a Hoover model 700. It was just the fan chamber and the motor nothing else. The plug that goes into the handle was how you turned it on and off simply by plugging it in. The older gentleman told me he used it as a leaf blower. I think I gave $2 or so for it. I used the motor in another restoration project along the way. I am very surprised to see another one!
--Tom