So, they are S&S Parkway ambulance lights. The seller's claim that they only need a "simple" bracket is a little....simplistic. The bracket comes up and curves over, mounting on the side of the light. I don't know where you'd find those brackets.
Nonetheless, if you need them, here they are.
(Not "Hess Ambulance" lights, I thought we were talking about the Hess gas station toy trucks! ;-))