When I look at the pic of the two 184s together it makes me think of a mid-1970s Dodge van ambulance I saw when I was a teenager. It had a red 184 on the driver's side, a clear one on the passenger's side, and a Federal CP-25 speaker in between. The siren was a late 1960s Federal PA15A or PA20A with the low-pitched wail and yelp tones.