To find it, you'll likely need to:
1. Remove the lower dash panel: This usually involves unscrewing a few screws and possibly unclipping some plastic fasteners. Be gentle to avoid breaking anything.
2. Look for a small, rectangular box with wires attached: The flasher relay is usually a relatively small component. It might be secured with a clip or screw.
3. Trace the wires: If you can't immediately identify it, trace the wires from the hazard light switch. They will lead to the flasher.
Consult a 1986 Buick Regal repair manual or a wiring diagram for your specific model. This will provide the most accurate location and details. Online resources like Haynes or Chilton manuals might be helpful.