I was playing with my cheaper T6 that looks like this link: http://www.ebay.com....=item27fc186a9e
On these style torches the outer glass is held against the O-ring and head via a threaded cap. Its easily removable giving your access to the reflector area and to place a dichloric filter inside provided you get one 2mm or so smaller then the outer glass.
In terms of trying to get to the LED I found it almost impossible to take apart the head enough to gain access. For that one I can't pull apart without destroying the head but if I could recycle that waterproof metal body and install a new bulb module/driver unit could be an option.
I once had a similar torch (see e.g. http://www.diveright...ght-p-3380.html).
The LED was mounted on a unit that had holes to put the tips of some pliers in to unscrew it.
However, the thread was a left-hand thread instead of the usual right-hand thread!
You had to turn it as if you were TIGHTENING a normal thread in order to actually LOOSEN it.