Probably just don't keep record back that far and nobody remembers it.
I tried getting a manual from Riccar for a vacuum they made in the 1980's and they said they have no support for that model and tried to sell me a new Riccar vacuum instead.
I could only find this about the vacuum;
"In 1989, British-born James Dyson (inventor of dual-cyclone vacuums) and Canada's IONA Appliances (the predecessor of Fantom Technologies) made a licensing deal in which the company would manufacture and sell a line of commercial dual-cyclonic upright vacuums called Vectron, for SC Johnson Wax, on which Dyson held the patent. Two years later, SC Johnson exited the commercial vacuum business and IONA renamed the vacuums to "Fantom". 1993 brought a successful infomercial for the original Fantom vacuum. One year later, the vacuum offered a HEPA filter as an option. In 1995, the vacuum was renamed the Fantom Thunder (AKA Kenmore Destiny)."