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.