This is a Heathkit Electronics Model GD-18 Siren controller, late 1970s custom do-it-yourself kit. Previously used by a now retired Ohio firefighter. This unit was tested in 2022 and 2023 and works great! Mounting bracket included along with wiring diagram printed on base plate for easy installation. Requires 58W speaker for sound output (not included).
 
Perfect for a 1970s emergency vehicle restoration or for a current volunteer First Reponder vehicle.