Indicator tubes for transistor logic machines.

Is anyone familiar with vacuum tube indicators used on transistor logic machines? I recently found a small rack filled with small transistor logic modules. Each module holds a flip flop or two at most. The modules are small PC boards with a metal frame and handle. Test points give you the state of each transistor on the module. Several modules have some sort of visual indicator tube as well. These tubes are not much larger than a standard NE-2 bulb, but they more resemble subminiature vacuum tubes. The tubes are marked 01037 J3, each had four leads. Two of these leads shows a resistance of 9.8 Ohms, and appears to be a low voltage filament. One is grounded, the other is connected to a bus in the rack of logic. There is no 'getter flash' inside the glass tube, so they may be some sort of glow discharge tube. Looking at the insides of each tube thee appears to be a very fine V style filament and a grid-like structure, but I see no clear anode or plate structures. There are two thin 'wires' outside of the grid, one in front and one behind the central grid-like / filament structure.