Right hand tail lights were a dealer installed or owner Installed accessory they were sold as a kit with wiring, bracket and light, some states actually required them in that time period (just a couple). I am travellng so do not have access to my archive but I am pretty sure the right hand light details appear in several years of the Accessory Installation Manuals. The fuel tank wire runs under the cab and goes up to the tank through a grommet in the floor under the tank. Sorry I don't have a picture of that. You should be able to see the hole towards the driver side, the grommet is sold by most vendors.
