Here/attached-below is the factory/original conduit (it looks like a spring) from the body to a rear door on my 1954 Suburban.
The conduit wire/coil/spring-like-tube is thick, but the conduit bends somewhat easily. You will see a rubber grommet in the body and in the door. The conduit in held in place inside the door, and slides into the body when the door is closed.
