What class sub is this? Not SSN-21.
No, the Navy in it's wisdom cut short the SSN-21 class at only 3 boats because it said they were too expensive. So their solution was replacing it with an even more expensive SSN-744 class. Although I heard that by the time they got done with the Carter it's sticker price was in the $3.5 to $4 billion range.
The Texas SSN 775 (not quite USS Texas yet :) is the 2nd of the Virginia Class.