Re. LED replacement torch bulbs; I got one for my 5 D-cell maglite, when the LED replacement to fit that first came out.
It's still got the same Duracell batteries in it that I used when I fitted the new "bulb" - they expired 1999 so that must be somewhere from 25 - 30 years ago!
(And it still works perfectly, blindingly bright. A sad reflection on the quality of newer cells really, as I've had several far newer sets of duracells start leaking in things long before they were out of date).