2D is probably the most common. Run with 2 18650's li-ion with a adapter to fit the mag. Also you can run 2 32650's li-ion without a adapter.
You will have to shorten the tailcap spring in both. With 32650's you will also need to remove some of the lip were the spring sets in the tailcap.
Driver needs to have at least 8.4v input. Batteries are run in series. Heatsinks are available here on cpf and other places.
With the 3D you could run 4 Nimh C batteries with a adapter. You could use the
shiningbeam 8-7135 AMC driver. There are others that sell this driver here on cpf and other places.
My personal preference for throw with lots lumens is a cree xm-l with a rebel reflector installed. The D led mags have this reflector in stock form.
There are lots of threads on cpf that have covered this topic very well. The mag is probably the most modded flashlight here. Search cpf and you will find lots of helpful
post.