Don't hold me to this, but I think what this might be referring to is what they called back in the late 60's or early 70' as a reverb unit. This was usually mounted in the trunk or where ever you found room and was connected to your radio, 8 track or both and created a delay between the front and rear speakers giving a echoing type sound to simulate stereo. I remember one of my friends installed one of these units in his at the time new Pontiac Tempest. It really didn't sound too bad for the time. Something different that didn't last very long.
Chuck Speake 1970 Chevelle Malibu Glen Ellyn, IL
