Just checked the TSC 3AA light and it won't fit a D cell either.
-Garry
I’m not sure what you’re attempting here, but the simplest and cheapest way I’ve found to make a 1-D light is to add a dummy battery to a regular 2-cell flashlight.
Welcome to BLF! While that is an option by making a real 1d size maglite you get a much smaller light.
I was on Amazon earlier searching for a pocket pen light when a comment I saw there caused me to make a search, which in turn showed me the existence of this forum.
My point is that a person can already buy some mighty good small & bright lights. And if I want “really bright” in a Maglite I’ll reach for my Malkoff mod.
The main reason I’m so partial to the Maglites is that that they’re built like a tank, and can produce a decent focus from whatever kind of bulb which a person happens to be using.
But getting back to the old D-cell models, what I want from them is long run time with decent light output. From what I can tell, the old PR4 bulbs put out about 7 lumens with brief bulb and battery lives. My favorite ‘fix’ for both issues is to replace the incandescent bulb with a low-draw LED so as to get about the same light output, but with a vastly longer run time. As it happens, Eveready sells a really cheap and crappy 1-D LED flashlight whose only saving grace is a PR-shaped bulb using only about 60ma. In my old Maglites (along with that ‘dummy’ battery) these will run for a very long time. And with a nice spot!
Long runtime has become a bit of an obsession with me. I want my emergency lights to be something besides candles or kerosene lamps, and I want that them to be so cheap I can have them littering the house. Besides the 1-D flashlights, I’ve played with the Pak-Lites. Hanging on the wall in the other room is a “basic” model I’ve snapped onto an 8-AA holder. For disposables I fill it with six batteries and two dummies - 9 volts. For rechargeables I use 8 batteries - 9.6 volts. At a measured 20 ma (the 9v level) I figure this combination will last.
Finally, a recent discovery - the solar sidewalk light sticks. Except for running into some on a closeout table for 90 cents each, I’d have continued to ignore them. But at that price, what the heck! - I bought one. Inside was nothing except a cheap AAA rechargeable. I replaced it with an AAA alkaline, then turned it on in a closet to see what would happen. The freaking little thing burned for several days, day and night! Back to the closeout table and scoop up the rest. They’re getting modified with a tiny hole in the side that’ll pass through the power wires to an outside D-cell. I’ve no idea how long a runtime these will have, but with a draw of about 13 ma/1.5v, it ought to be awesome. I’ll hand these out to relatives at Christmas as “ice storm” lights. 
It's a pleasure to have you onboard, Zachary Smith!
