The modification carries a value of $208.6 million.
The items to be purchased include steam and electrical-plant components, main propulsion units, ship-service turbine generator sets, and miscellaneous hull, mechanical and electrical-systems components to support construction of the three submarines -- the SSN-793, SSN-794 and SSN-795.
Construction of the SSN-793 begins next year, while the other two are scheduled for construction in 2015.
The modification is to a contract originally awarded to General Dynamics Electric last year for the submarines. With this modification, the overall contract is worth $595 million.
"Recognized as a model defense-acquisition program for its technical excellence and schedule performance, the Virginia-class submarine program provides the Navy with the capabilities required to dominate both the open ocean and the littorals," the company said. "In partnership with the Navy, Electric Boat is driving innovative cost-saving efforts, without impacting capabilities, through overall efficiency improvements, decreased ship-construction labors costs and shortened ship-construction cycle times."