Tail light, replica Lucas 525, the early and narrow model.
Tail light with brake light. Mounting studs are 80 mm apart.
Part numbers: 53269A, 525, 018760, 109497
Supplied as standard with a 12V - 2.3/8 watt bulb.
See item number: 21.G.2 for a 6V - 2.1/3 watt bulb