I'm 99.9% sure I know what truck that is. Is it supercharged? If it is the one I'm thinking of, it was built by a guy over here who owns a body shop. It was a originally a half ton, and he converted it to a dually and lowered it. The clip is off of a Tahoe or Suburban. Since the frames are slightly different between the 1500s and the HDs, I don't know if it would be a bolt on to a 3/4 ton or 1 ton. I can ask him if he knows.
I just found it on eBay. It is the same truck.