I have a old incandescent model and I took the whole bulb module out and it looks like this LED module below will work, maybe. I'm not %100 certain but it looks like it would work. The biggest issue I see is maybe with the reflector it looks like the hole for the bulb may be to small for the domed LED but it looks like if you remove the red o-ring that sits around the bulb in the reflector you may have enough room for the LED.
If that don't work you can order the "Facecap assembly" that includes the bezel and reflector, the question with that is will the threads work with the older Strion model. Maybe someone else can chime in here who has attempted this, you can also take apart your Strion and have a look at everything and see what you think. You might get some answers from contacting streamlight or copsquest.