Thank you for the clarification David.
tobnpr, gatling guns are title 1 arms. (Not machine guns.) If* the motor was registered as a post sample it could be used to make the (not a machine gun) gatling gun fire full auto. By removing the motor the gatling gun would once again be a title 1 firearm. It never would or could be a transferable machine gun.
*I have heard stories from old farts at the KCR shoots about registering 110 volt drill motors as post samples for the exact purpose of making a hand crank .22 gatling gun have an on/off trigger rather than a hand crank trigger. These stories could be BS. They could be true. If they were, I don't know if the BATF would let something like that slide these days.
However, if the junkyard owner bought the electric powered gatling machine gun (post-sample machine gun) , he is obviously in possession of a Federal Firearms License of some kind.