Considering the size, I'd hazard a guess it's Crosley-powered. A few of the companies that owned the rights to the Crosley engine after Crosley stopped building cars (Aerojet, Fageol, etc.) did build them in inboard configurations such as this.
Thanks, Dan, for my first comment! You are hereby qualified to enter the motor life.blog sweepstakes, for a grand prize of one dozen used Renault 16 half shafts.