Nice discovery. Did you dremel out the Legend bulb holder?
I recently purchased a 4D Legend, and yes, I needed to Dremel the bulb holder and the reflector for everything to fit.
I also realized I didn't have a charger that D batteries would fit. Quick! Off to Amazon.
One 4D Legend Flashlight - < $7
Nitecore Charger - $18.95
Four Tenergy Batteries - $32.10
Malkoff XM-L Drop In - $80.25
Total = Flashaholic