This pair of complete rear lights are currently on eBay.
They are not the correct housing units so they’d need to be trimmed to fit a Type 46 S1 or S1A.
(these may be of use if you’re creating a Type 47 replica from a later car?)
I have no connection with the seller.
Lancia Flavia Carello Rear Lights: Lotus Europa Type 46 47 GT, S1, Zagato Sport
https://www.ebay.co.uk/itm/223980586073