Todd Lappin's mystery machine

Picture 7-4
Todd says: "I bought this today at a flea market for $30. It's US Navy surplus, and it came in a heavy steel case. When I plugged it in, it began whirring and clicking, and (joy of joys), the Nixie tubes started blinking numbers in a wonderfully erratic pattern. Can anyone tell me what this thing is?"
Link (Don't email me to tell me what it is — post it as a comment here.)