The tail lights are sold individually as LH (left-hand) or RH (right-hand).
The LH tail light is the one of the driver side of a left-hand drive (LHD) car, like in the US.
The RH tail light is the one on the driver side of a right-hand drive (RHD) car, like in the UK.
The tail lights for the “Gaydon-era” V8 Vantage, V12 Vantage, DB9, DBS, Virage, and Rapide (and all their variants) are interchangeable. Programming is not needed when changing tail lights.
Installation is a DIY job that only requires a few basic hand tools and maybe an hour or so. An installation kit is included when ordering from Redpants!