Those end grilles/speakers came with any radio that had stereo capability, which is usually an am/fm multiplex radio or any radio with a cassette or 8 track player. Your Brougham had the cassette player on the transmission tunnel, but usually was accompanied by an am/fm multiplex radio in the dash. Sometimes Chrysler had an 8 track player with an am only radio, and that too got the two extra grilles/speakers on both ends of the upper dash pad because of the tape player.
