I add a Gato for the Player's sub, but I get a Gar?

[Snacko]

I add a Gato sub to the game, and assign it as Human Control. But in the Single Missions screen it defaults to a Gar sub, and Gato is not even in the list of subs to pick from.

I have been confused about this for a while. I seem to add specific subs, but others appear as the Player sub. I assume it has something to do with the dates of the mission/sub Entry. What gives?