A Beamco "Grand Central"! Longtime California brand, I believe they were self manufactured and installed (a la Sequoia, Omar's in the PNW, or Budd in NJ).
I believe these use a permanent cloth filter, right? Have seen one installation that had two canisters...one like yours and a second one with no motor as a pre-separator piped in series.
Grand Central's big unique feature was the ability to both trigger the power unit to activate and then supply 120 volts for the power brush, through a single two conductor "low voltage" wire. The wall inlets and hoses had a special "headphone type" connector, and the control module in the power unit was unique.
My understanding is that MD was in negotiations to buy the company in the late 1990s, to get access to their patented switching technology, but it was contingent on their getting UL approval. They were unable to do so, and thus the acquisition did not go through.
The company is gone now, but I am not sure when they ceased operations.
Can you post pictures of the inside of the power unit, and the ends of the hose?