I know McGraw Edison was still making box fans at least in 1984, they had Toastmaster box fans into the 1990s.
I know Westinghouse and Emerson stopped making portable fans in the 70s, and Hunter did in the early 80s.
And yes GE sold their small appliance division to B&D in 1984, but I agree I don't think I've seen GE fans from that late.
I have a black GE Vortalex with three aluminum blades from the 30s I'd say, a gray GE with four stamped blades from the 1950s, a similar smaller one in beige with a tighter cage from the 1960s, and a larger one with the tight cage and 5 blades from the 1960s or 70s. I also have two of the big beige box fans with the 5 blades, both 3 speed.