The news ends speculation that the Melbourne-based Fortune 500 company was looking to move its headquarters out of the region after its recent acquisitio n of McLean, Va.-based Exelis Inc. Harris Corp. has been headquartered in Florida since 1978 and has had a significant presence in the state for more than 65 years. The company today has about 6,000 Florida employees, including 3,200 engineers and scientists, and is the only top 10 defense contractor headquartered in the state.