Years ago I had an '80s Plymouth Sundance that had a second tag that had SPECIAL HANDLING or maybe SPECIAL HANDLING UNIT on it. It's been so long I've forgotten which now. Anyway I thought the tag was unusual but couldn't find anything out of the ordinary about the car. It was a plain red 2 door with a 2.2 and 5 speed manual trans. I don't recall it having a particularly low serial number either.
I wished later that I had kept the tag when I sold the car.
Dallas