The first link in the thread has a CW 3-18V for $2.07 ww is $1,97
Certainly not a $2 upgrade, but I instantly think of Brian’s (kyfishguy) builds when I hear about building up Maglites. If nothing else, a read through some of his threads will be educational. He’s got some good descriptions and pictures of his work.
I could not find the W/W in the 3-18v range option.
I ordered a “1200” lumen LED piece for a fenix or trustfire light. it was like $6 so I think I can mod it to fit They say it’s 3.7 volts, so I am assuming it’s for a 1x18650 light but for a 3 D cell it should by good to go.
These are great for long runtime and emergency backup. I have a few stashed in various kits. Beware, though. Brightness is not there (obviously, 30lm) and the color tint is angry blue. Would do very well to have a mix of D and C cell maglites and/or lanterns to use these with for emergencies.
Re Walmart cheap led bulbs I have a couple of those in old explosion proof Rayovac flashlights. The output is terrible but I saw a test of the runtime and it was days, I think the tester just gave up