Unlike most Leslie speakers, these cabinets are unamplified, acting as an extension speaker for an instrument amplifier.And unlike other Leslie cabinets, they take 1/4" phono plug inputs, like a guitar speaker cabinet.
And they're built like guitar cabinets, with a Tolex covering, sparkly grillcloth, and handles, while the classic Leslie for organs is an elegant piece of hardwood furniture.
Most likely, the intent was to give players of "combo" organs (e.g. They already had amps, so all they needed was the cabinet.
(You could get one of those, if you can't find a Vibratone.) The Fender Vibratone is a variant of the Leslie Model 16 and 18 speaker cabinets.
(CBS bought both Fender and Leslie in the mid-1960s.) Like other Leslies, the Vibratone contains a rotating drum mounted in front of a 4-ohm speaker (a 10" in the case of the Vibratone and Leslie 16; a 12" in the case of the Leslie 18).
They all produce phasing effects by firing their speakers into rotating diffusers which bounce the sound off of everything around them.