Pila GL4 upgrade to LED?

[Chickensnickers]

I’ve had this GL4 for a LONG time. I’m looking for a drop-in solution to get more light out of it: with fresh cells the light output is worthless. Bonus if there is a way to run 18650s with new LED.
I search the forum and there is too much and too old info. Maybe Im a bit lazy but not totally...I did try. I would consider sending this off to a Dr Flashenstein for upgrade surgery if it wasnt too expensive.
Can anyone give me the definitive word on an economical route to better light out of this thing?
Thanks

[Eric242]

Iirc the GL4 uses a D36 dropin that "should" (?) be replaceable by standart D36 LED dropins, unless you have a LED switch instead of a clicky. Check Lumensfactory, they usualy mention if their Dropins can be used with the GL4.