To reduce an overwhelming number of hits via an online search, often one might limit the search to within a geographical area.
I believe that you might be able to use an E10-base LED bulb; the E10 meaning the miniature screw Size or mechanical interface.
The bulbs would be offered in various Voltage or electrical ratings — and that feature one needs to select; (more on that later).
The bulbs come in various Brightness or luminosity ratings, sometimes with only 1 diode, or more-omnidirectional with 5 diodes — requiring more power (volts).
So, if one chooses the 1-LED bulb, one may find a bulb with the electrical rating of 3-volts (or similar range) to match the typical output of 2 regular D-cell batteries.
But if one chooses the brighter 5-LED bulb, one may also find that additional volts would be required.
There are battery-Adapters that squeeze 3 smaller AA-cell batteries into a housing that has the physical shape of a D-cell. By using such adapters, one may triple the 3-volts output of 2 D-cells to 9-volts with 6 AA-cells. I have even mixed a D-cell with 3 AA-cells (w/ 1 adapter), for 6-volts (1.5 + 4.5).
One feature which I have not investigated much, is how LEDs might be diffused, and perhaps thereby working better with parabolic reflectors behind the bulb, as well as any Fresnel-type focusing lenses in front of the bulb.