I was right, then wrong, then right again.
In Indiana:
(b) A motorcycle manufactured before January 1, 1956, is not required to be equipped with a stoplight under subsection (a) if the motorcycle is not operated at the times when lighted head lamps and other illuminating devices are required under IC 9-21-7-2. Insert- IOW-Daylight!-
(c) This subsection does not apply to a motorcycle or motor-drive cycle. A person may not:
(1) sell;
(2) offer for sale; or
(3) operate on the highways;
a motor vehicle, trailer, or semitrailer registered in Indiana and manufactured or assembled after January 1, 1956, unless the vehicle is equipped with mechanical or electrical turn signals meeting the requirements of section 17 of this chapter.
So regardless of whether it came with them (Federal) or not, Indiana does not require them on a motorcycle. (State).
The fine print on these laws is ridiculous. Hope you can find your State's rules.