Superformance dealers have them. I modified my SPF lights even further by trimming the retainer plate, opening up the hole in the body of my ERA, using a halogen bulb for the stop-lamp, and rewiring the car to accept two bulbs with separate functions for stop/turn and taillamp (using the brighter halogen bulb for stop/turn, and a standard bulb for taillamp circuit).
Made a significant improvement in rear lighting.
regards,
Jeff