I picked this Surefire up on a whim.  

Input is appreciated.  I have tried to look it up, and find out relative vintage, but haven't gotten anywhere.  I thought it was cool, and it worked.  I have a few lamps from past deployments that fit this, so figured, "what the hell?"  

The mount that came with it is in the pic.  

Thank you.  

You might have better luck asking at candlepowerforums.com

Looks like an older Surefire 6P model

I'm gonna guess, a Surefire 3P with an extender and a weapon light head.
The weapon light head is to provide recoil absorption to protect an incandescent bulb.  Its a little bigger and heavier then you need for a good LED drop in.
I'd get a Malkoff LED drop in if budget allows.  If budget doesn't allow, google ultrafire.  Malkoff is for duty use, ultrafire is not.

Edited to add, I'm not really guessing.  It's either surefire, or a clone.  Whats cool about it, the parts are interchangeable between a few different models.  You can mix and match between quite a few different Chinese clones too.  Google Solarforce.

Yes, Surefire 3P with one cell extender and shock absorbing head.

I retrofitted my MP5 Surefire with a Cree LED emitter - night and day.

It's a Surefire 660.