Like I said earlier, you can still buy replacement belts for your Supervac 180 since it has much of the same mechanicals as the Kirby 500/Sanitronic line. It is only the 18" brush roll that is NLA, along with a few other peculiar parts.
And, regarding your Royal Classic upright, I am wondering what is the exact model # on its nameplate (which is affixed to the back of the nozzle by the front wheels)?
Here's how to determine its age:
1989-1990: front of bag will read "CLASSIC" (with "1989" on machines made before November 1989). Motor specs: 6 amps, 6 blade fan. Front decal will read: Royal COMMERCIAL QUALITY which encompasses the entire angular part of the housing where the Adjust-O-Rite/belt drive is. Model numbers will be 9005 or 9089.
1990-1991: same burgundy bag and front nozzle decal as models 9005/9089, but new motor specs: 7 amps, 9 blade fan. Model number will be 9700.
1991-2002: revised COMMERCIAL QUALITY decal (no longer borders the whole angular part of the nozzle where the Adjust-O-Rite is). Model number will be 9700 (7 amp motor) through 1995, model 4000 (10.5 amp motor) from 1995-2002. Bi-lingual English/French warning label is used on 1994 and later models.
~Ben