On your 1950 truck (I had to look at your previous posts to find out - otherwise would have to guess-- That's a hint to put your truck info in your signature - or at least tell us what you have) you can pull the passenger's door lock and get the 4 digit code off it and give that to the locksmith. The lock comes out by pulling back the weatherstrip and pulling the keeper out of the door. The number will be on the shank of the lock. If your truck has the original locks, that key should fit all three locks.
Otherwise, follow Otto's suggestion.
