turn signal

Does anyone know where I can buy an original size flasher for my 78 Trail 90? I’ve included a pic of the one that came out of it and I have a new one that works but it does not fit in the little rubber band that holds the original flasher in place.

Anybody ever installed turn signals on an old CT70. I have a Sapphire Blue 1971, so it was not manufactured with turn signals. I don't know how possible if at all it is to install some turn signals onto it. Any advice?