Okay, so I have a lot of aa nimh's lying around and was wandering if I could use them in it. I know it's only 2.4v, but dont know if it will work like that. Thanks.
I don't see why you should have a problem, even with the lower voltage. I'm able to run 3 nimhs (and can run it via CR123) in a 4-cell Mag-lite 3 watt dropin (not sure how long they last, since I had all but 2 nimh's crap out, and 2 nimhs wont work with the driver, unfortunately).
Assuming you're using a 2-cell dropin, and not a higher one, I don't think you'll have a problem, as long as you have the right adapters, like Raven said.
As long as the voltage matches, it will work. The 2D has a boost circuit, so as long as the battery voltage is below the LED's forward voltage and the battery's voltage is above the circuits activation voltage, it will work.