Dazl-Ray was a brand many years ago. Never part of Whelen. One of their lights was used on some wreckers(OPs name?)
It was a DR-2, had a glass dome, a sealed beam bulb shining up, with a rotating reflector, with the motor in the top of the dome. I wonder if this is the light in question. There was a wrecker picture posted a while ago that had this light on the roof. I have sold a couple of these lights. Nice lights!!