[rotorwrench]

Most all of the Fords cars in that era had a similar latch mechanism. It's likely the type with the rotating star wheel that meshes with teeth on the door jam. They have a metal arm that actuates the latch on the inside and a simple lever actuated by the door handle button on the outside. I'd hate to have to destroy a door panel but that would be better than destroying the sheet metal of the door or B pillar. Something is likely broken in the latch mechanism. Now finding out what is another matter. Then how to manipulate it to get it to free the latch is yet another. You will have to have access to the latch somehow. The door will have to be opened up to repair it since some of the screws are in the door jam area. If you take the lock knob off the shaft, you can drizzle penetrant down in the general area of the latch and possibly free something that might be corroded or crammed with debris or the like.

Most body types are obvious on the mid 50s types. They only made one fordor, one convertible, and one wagon. The tudor had three or four different types if I remember correctly. Any other changes were upper or lower trim levels on the different body types like customline, mainline, crestline, etc.

I would have to assume that you want to know the trim level and what type of running gear it had when new.

PS: I forgot the 2dr wagon types so add that in there too.