Your unknown shuttle looks like a Photo Sonics Acme to me. They liked to stamp the serial numbers on the tang. Acme also had tab on the outside of the base plate to set into the Camera door when closed. I had one in 8mm and super 8mm and the cam was lower than that in 16mm like the one shown. The shuttle took masks and shot both sides of Double 8. BTW the Printer and Camera shuttles have registration pins in different positions and some are in 35mm are set up with KS 1870 perfs instead of the standard BH 1866.
