These units are not always a generic fit and this one fits the left side mounting point on the 54’s curved dash. 

I don’t have any way to test it (the auto dimmer functions on my Cadillac are located inside the drivers side fender) but the tube looks good and all of the wiring/lenses are intact. The lens has a small crack but a dot of super glue would fix that easily. 

You’ll still need the relay and amplifier housing to actually use it but these things were really finicky, even when new. Even without the other parts, it looks great having the car, as ordered form the factory, complete with that option visible on the dash.