The 903 did not have the removable nozzle, but the 980 did. Nonetheless, you did find another rare Royal metal upright. My 786 Prince has the same red trim.
Have a royal 880 and a 888 nozzle with a belt lifter. I'm going to modify the vacuum so the removable nozzle will work on my 880. It's going to need a nozzle latch. It's one of many projects I plan to do.
Would like to see more pictures, but since you have a model 903, I'm thinking you actually have an Electro-Hygiene, with a Royal bag on it. Here's pics of a couple of my 903's. The one with the red bag with silver printing was from 1976, the one with the beige bag with red print was built in 1983.
Jeff
BLUE 880.............HAS CAST TABS BUT NO HOLES OR BAR
BLUE 604
RED 891306............COMMERCIAL
TAN 4000.............COMMERCIAL
BLUE 6712............HEAVY DUTY COMMERICAL