General Dynamics to Buy 2 Lockheed Units

General Dynamics Corp., continuing the expansion of its defense manufacturing businesses, agreed to pay about $450 million to acquire two units of Bethesda, Md.-based Lockheed Martin Corp. that make combat vehicles and gun systems. Falls Church, Va.-based General Dynamics, which builds nuclear submarines, surface combat ships and armored vehicles, said it is buying Lockheed Martin’s armament systems unit, which has plants in Burlington, Vt., and Milan, Tenn., and its defense systems unit in Pittsfield, Mass. The armament systems unit, which has about 1,600 employees, manufactures advanced gun, ammunition handling and air defense systems. The defense systems business has 1,650 workers.