While reading the article “Secure Signals for a Survivalist,” by Fred J., I keyed on his reference to the lightening-up the good old USGI angle head flashlight.
As far as lightening-up one of these, I think I have most people beat. My first upgrade for mine was in replacing the old-fashioned incandescent bulb with an LED bulb upgrade. They’re pretty common now, as the Army issue flashlight uses a standard flashlight bulb. That made the flashlight produce literally ten times as much light.
The second upgrade was created by sheer luck. In an infant rocker we were keeping for some relatives at our house, I discovered adapters for AA to a D-size cells, allowing you to use AA batteries in a D cell battery compartment! However, since I already had the LED upgrade in my flashlights, I installed these in both of them, and now my Vietnam-era USGI flashlights weigh virtually nothing, producing the same powerful amount of LED light!
PS: Hang on to those old incandescent bulbs, as an EMP/CME-rugged backup. They will also still work with the AAs! – Snuffy