I have no Prolux 1572C, but I know that there were two different versions and corresponding name IDs: "Prolux Electrolux" with an 8.5A HP motor and "Prolux Commercial by Electrolux" with the original 8.1A Electrolux L-shape upright motor. I suspect that the "Prolux Commercial by Electrolux" version was sold through a distributor such as a catalog or warehouse line. I believe the only difference between the household models and the industrial ("commercial") Prolux was that the latter was equipped with a 40-foot double-insulated cord versus the 30- or 35-foot double-insulated cord of the former. The Prolux line was manufactured from 1987 to c.2000 followed by the commercials.
I did own two of the "Lux Commercial by Aerus" uprights which both had the same model ID, but the older had a conventional motor and the newer one had a JEI motor which was louder; albeit both were rated as 10.0A. These came with illuminated SPIs (System Performance Indiators) on the hoods, ergonomic handle grips, 50-foot grounded cords, a replaceable bumper, and more durable hardware. They were a cooperative venture with ProTeam, Inc.; I know both companies contributed to the design, although I'm unsure if manufacturing was also shared. Their performance was satisfactory, but I much prefer Windsors or Linhauses with their attached hoses and stronger performances. I got rid of the Lux Commercials when I moved a while back.
Both the Prolux industrial and Electrolux or Lux Commercial had a half dozen or so successive models as changes and upgrades were made. The Prolux ratings, as you know, are inked on the top of the hoods like the household models; while the Commercials' are stamped on the bases. Each was equipped at the factory with two serial number decals on the outside of the bag casing like the household models—one visible and one protected under the handle. These include a 2-letter series and a 5-digit production number. The only way to determine the production time would be if there were a shipping record which listed them. Aerus's serial number database does list the corresponding original dates of sale, but these may or may not have been the same years the cleaners were made.
See this archived thread I posted about my Lux Commercials, if you'd like more information:
https://vacuumland.org/threads/lux-commercial-new-to-me.35429/