Tail lights rusted out

Hi All: I need some help. This is on a 1973 Sarfari Land Yacht. The tail lights are rusted out, not much left, light sockets are gone. Need to get access to the wires under the light housings to rebuild. Appears there is a cast alumimum piece the lights are mounted in or if you could remove this piece you would have access to the tail light wires. Any help would be appreciated, I am worried about this.:blink: