Rob -
A DEC Part Number would speed up your Part Search.
Radwell, a surplus dealer in New Jersey, lists a DEC terminal Flyback Transformer.
DEC Part number: 16-27975-01 (supposedly used in the DEC VT320 terminal)
https://www.radwell.com/en-US/Buy/MONITOR%20TECHNOLOGIES/MONITOR%20TECHNOLO…
A quick search on eBay produced this flyback candidate by Dalbani, a Miami, FL reseller.
eBay auction # 123532693525
Replacement 16-27975-01 Flyback Transformer for DEC CRT TVs.
Please verify the part number to ensure compatibility. These Items are not manufactured
anymore. Order before we are out of stock permanently. All items are new old stock and
guaranteed for functionality.