Turn signals acting weird

My 66 Belvedere has just recently changed from "frantic" to "flicker strobe".
Bought new flasher unit.
Really sedate timing.
New unit does not fit dashboard clip, I will be looking for old style heater/clicker specifically now, and check diameter.
Back to old flasher.
Still getting used to the frantic thing, it's
impossible to mistake for brake lights, though.