the separation of turn and brake happens in the signal unit, the wire from the brake light switch [only one, the other is from the power point] goes via the signal unit, not direct to the rear lights, the selected brake light becomes the turn signal while the other brake light functions as normal .... if you want something looking more "vintage" you can look around at what's available [
2 at the bottom here], back in the day the only thing available was the clamp on deal, otherwise you might consider a toggle switch under the edge of the dash
Bill
