I agree, it's unfortunate that Imperial didn't tout the importance of the 50th Edition, you know like 1 of XX or even special gold badging somewhere on the car. If someone didn't tell you, or were one of the 57 original owners, you'd never know. You could raise the bullshit flag and if the greasy car salesman didn't know the options list he'd have a very hard time proving it.
Chrysler did designate these 57 cars as an Imperial "Crown Lebaron".