Here's a 1990 Royal 9100 which to me looks suspicious. Take a look at the third picture in the link below to understand my point.
I know this to be suspicious as no 9100 actually had the Au-Toe-Matic height adjustment system - rather that should be the Rite-Hite knob there. I know the front nozzle graphic where the Adjust-O-Rite plate is would be correct, as would the outer bag assembly and the handle/cord assembly... but it is the motor unit assembly that really has me scratching my head over the true authenticity of this item, even if the correct nine-blade (slip on) impeller fan is intact as well as the color of the adjustment pedal.
This leads me to ask: has Royal itself and/or its dealerships ever used up certain motor unit assemblies on non-matching machines?
Or one other clue: a possible misprint of the model number on the cleaner's nameplate applied to the back of the nozzle, as in should be 9000 for it matches perfectly with the Au-Toe-Matic height adjuster.