I have dual Whalens on a licence plate mount. I dont remember where I bought the mounting plate.
I get lights from Sirennet.com. Same as Whalen but much cheaper They sell brackets too for the lights and they BRIGHT!!!
Get the SNGL models. They are programmable to do a dozen different flashing programs and they can be linked and synced
http://sirennet.com/store/cat/category/leds