Tail light Aprilia (unknown model number)
Moto Guzzi V700, V7 Special, Ambassador, 850 GT, 850 GT California, Eldorado, and 850 California Police models
Thanks to Charlie Mullendore of Antietam Classic Cycle for sending me this information.
This tail light was used on some Moto Guzzi 850 GT models. Note the bracket is different as well (a CEV unit). The lens is labeled
Catalux with the number
02 8169. Reproduction tail lights and replacement lenses are available from Guzzino. Guzzino also carries a bracket that may work.