There are TWO (2) branches in United States, one is in MASSACHUSETTS (where Boston is) which is the FIRST BRANCH (not the headquarters itself) and another is in NEVEDA (where Las Vegas is) which is the SECOND BRANCH.
Unit 3 was made in the FIRST BRANCH, and the Unit 4 was made in the SECOND BRANCH. The Unit 04 and SECOND BRANCH disappered during the installation and testing of the S2 engine. The cause is UNKNOWN.