Which Key? Ignition or Trunk...
 

Bought a 66 Dart with two keys, one opens the trunk & one works in the ignition. My question is which one is also to operate the doors from the factory as neither of them seem to be working...

The ignition key is the same for the doors. It could be possible its had the locks changed or the ignition changed.

The trunk key is all by itself

T -

The ignition/door key should have a pentagon head, the trunk key has a round head.

Like blue said, the cylinders might have been changed or he had new keys made.

Archer

Or they might just be really badly gummed up. I'd try a squirt of just about anything that won't hurt the paint, including 'ol WD

If the key still won't work,just take out the door lock cylinders and bring them to your local locksmith.They can be keyed to fit your key.

Or, if you feel lucky, you can just pull the door locks and look at the sides. There's a flat plate that has like 4 prongs holding it on. Pop that plate off, remove the flat inserts, and you instanly have the locks working with any key. Most people won't just randomly walk up and try keys to see if they fit, so once you lock them, people just assume the doors are locked.

The inserts are numbered, and if you have one lock that works, and one that doesn't, you can use that to change the tumblers to the correct ones if you have a supply of inserts. I did that on one of my b-bodies, many years ago, but the last 3 I've built, I just pulled the tumblers, and never had anyone open the doors.

Great info! Took your idea but didn't feel safe with removing all the tumblers as you can just unlock the door with anything. I pulled all the pins and set three of the five to work with my key so I have more security.