The present invention pertains to lighting device systems or methods applicable to off-road utility vehicles. The concepts include light sources for light beam production, a housing enclosure that encompasses internal elements and includes opposing front and rear portions. Inventive concepts further include a heatsink arrangement along an outer surface of the rear portion via a fastening system that is configured to transfer generated heat from the light sources and includes a sealing member with fasteners for securing the heatsink through the housing such that the sealing member becomes positioned between the heatsink and interfacing housing structures.