As a ex "wrecker" driver I think I can speak first hand of what light is required:
You have indicated that you want a holster mounted light.
This would not be my preference but to each their own.
My mag 6D was always my light of choice for a number of reasons (illumination was not a primary reason) but for a smaller belt holstered light I would say the M20 or M21 would be good contenders.
I would recommend a diffusion lens/mod for either as they both would produce excellent area lighting (and more than enough throw for urban areas) for those areas you wrecker recovery lighting does not cover. Assuming you have high mount lights on the bed of your tray or boom that should give excellent cover out to the full extent of your winch rope.
It would be my experience that also suggests you do not want a spotty thrower as this is a real pain in the butt when doing a recovery at an incident with lots of police/ambulance/fire etc in attendance. With the modern LED spotty thrower you will likely get a less than favourable response from an attending police officer who gets that in his face!
Not to mention the glare you get from this type of light from reflection.
The last thing I would want is glare from a thrower whilst hooking up recovery chains to the undercarriage of a vehicle.
I would not be going for anything smaller than a M20 size unit as I know it needs to be long enough to comfortably place under you arm pit whilst filling out all the paper work or operating booms/trays/winches/feeder-pry bars etc.
I have a M20 & M30 and I personally would be going the M30 but it is not a comfortable holster type mount of light. If I was back on my truck in this day and age I would probably have a M20 or similar clip mounted to my chest pocket (I could not imagine climbing in/out of a cab all day with a holster mounted light) just my leather man was enough. And I would have an upgraded LED 6D mag. Somehow I can not see anyone using a single 18650 light to help feed a wire winch rope onto a drum.
Just my 2cents worth......there are so many choices today
