Tell me about this flashlight...

Ok, so I've got a Surefire L1, and I believe it's a Gen 1. I need the help of the vast flashlight knowledge the members of this forum posses.



What I can tell you about it:



--it's at least 4 years old

--had a white dot on the base of the head denoting white LED

--throws a completely square beam with zero spill

--low setting may only be a couple of lumens

--high looks to be about 25 lumens when compared to other lights I have



Here are my questions:

--how many lumens is it really?

--can I replace the head with the head from a new L1 or better yet, a Malkoff to get more light?



Thanks!