Sounds like you're describing a Leslie cabinet. They are designed to amplify organs -such as Hammond organs, like their B-3 and C-3 models. The motorized baffle is controlled by the organist -it has 2 speeds to create 2 different sound effects for the organ, and also spins the high frequency horn inside the cabinet. Just google Leslie cabinet.
info about 1970's leslie stereo speakers
I resently purchased a pair of Leslie plus 2 model 450 speakers. They are from the early 1970's. I'm am searching for info about them, such as what they may have sold for new, can they be used as a two speaker system. I have learn that they were sold to be use as an addition to a stereo system to create 4 chan operation. The main speaker has two 50 watt amps built in them and each speaker has some type of a motorized baffle under a 15 inch woofer. Any info appreciated.