He said the full model number is WGM3392-UOGS21B. I'm trying to find more info anything as well. Based on the pics it's seems indentical as my D9200.
This is what the seller said about it. "WGM3392-UOGS21B. 33" 9200 series digital monitor. They were not very common, but again, if your 27" 9200 works, this should work; same boards and layout, with a few component changes. I had PNL (monitor repair company in California) convert a 33" board set to work with a 27" 9200 tube"