While doing a little surfing I ran into this page on the Concor site.
I remember watehing and riding these as a kid and until I was about 15-16 which would be teh mid 70’s. They made a distinctive grinding/whining sound when they slowly sped up.
Funaro & Camerlengo also has MP54s. There is a way t power them, they were discussing it at one of the shows I was at.
–Randy