If it's just the lock cylinder and keys, they were the same from 1949-1966. Standard/Blue Streak (and others, I guess) still make them. Check your auto parts store.
If the wire insulation in the armored cable fell apart (failry common), you can substitute a '53-56 (approx) lock assembly. They didn't use the armored cable, just regular wire with a terminal.
If you have a lock without keys, any good locksmith can make a key by 'impressioning' the lock. If the locksmith doesn't know what that is, find another locksmith!
Also, in order to remove the cylinder from the lock body without a key, have the existing cylinder picked by a locksmith, then turn the cylinder and depress the brass pin. Some people use drilling or forcing, but that can break the rest of the lock.