A light bar has several modular light source heads which may contain different types of light sources as well as different technologies mounted in cages by shock absorbing grommets. The cages are mounted on a bottom member so that the heads can be arranged along opposite sides and the ends of the bottom members. The heads are captured, and assembled with the bottom member, by a top member which also captures translucent or transparent members or lenses along the sides of the light bar and, transparent or translucent end caps which may also provide lenses for the light source heads at the ends of the bar. The end caps are removably connected to the top and bottom members at the ends of the bar by screws extending through the end caps. The light source modules have the same wiring connected thereto by connectors from a connector board to connectors along the back ends of the light source heads. The top member is attached to posts extending from the bottom member by screws so as to enable removal of the top member to expose the light source modules. The modules at the end of the light bar are exposed upon removal of the end caps thereby permitting the light source modules to be installed, removed for servicing, and the interchange of different modular heads to obtain a desired compliment of light sources, which may be of different types and technologies, or may not be installed if desired to meet customers' orders.