If anyone of you have at least 2 of 3 or all 3, can you confirm that all 3 heads and bodies are all interchangeable? Some pics would be nice to see how they look. Since all the electronics are all in the head, I suppose swapping the body, if they fit, won't affect the brightness/runtime? Besides, anyone notice if a certain type of battery will fit in one but not the other? Is there a length difference among the bodies?