You can get the patch from Ubisoft's official site - I'll include the link at the end of this post. You don't need to get the first three patches btw - 1.4b is cumulative.
(the old ones aren't available anymore anyway). After installing the patch, you will then see the threshold value for the gun crew in your .cfg.
Also, make sure to get the correct patch. There are US and European versions, and versions for online-purchases vs physical copies.
http://www.silent-hunteriii.com/uk/updates.php