Here is a 10 LED Brake Light designed to be used for vintage and classic cars. It operates on 6 and 12 volt systems, positive and negative grounds.
It is very rugged and durable. The entire light is encased with epoxy inside an aluminum channel. It flashes for a fixed period of time, and then goes to a steady on. Steady on only versions are available too upon request. http://www.brakeflasher.com/brake_al.htm