These locks are not replaceable. I've got one on mine and the lock is good, but the outside locking cylinder is long gone. That outside refrigerator handle is cast and they tend to break eventually. If the lock itself is good and you have good inside and outside handles - I would keep looking. A lot of us are using locking latches as an extra measure to keep the door from flying open. On my 59 I mounted a latch on bottom of the door - so its kinda out of the way.
On my 58 I'm going to try to install a standard lockset - I know the purists will cringe, but it should work fine.
1956 Flying Cloud
Four Corners Unit
Albuquerque National Balloon Fiesta
Vintage Trailer Academy - Formerly the original