Update on the VFDs - Vacuum Florescent Display triode tubes/valves.
The display boards were salvaged from 36-bit mainframe CASINO project from early 1960s, then used in my Homebrew 6502 computer display.
Most used VFDs in this machine had NO markings! However found some spares used to maintain that original machine
that had two similar markings. CASINO was a 36-bit machine. I took a hacksaw to the PCBs, chopped them down to 32-bit.
Looks like ANODE/Plate voltage I used was 40v (needs physical verification).
Marking: two special symbols similar to "o" and uppercase "I", followed by 132D4 or 132C5
"Holland" 6977