1935-1939 trucks had a conduit installed on the wiring harness to protect the wires between he body and the tail lamp. On the forward side of the lamp there was a bracket with a keyhole shaped slot to receive and retain the lamp end of the conduit. I believe Jim Carter and other suppliers sell a reproduction of this item. The problem with using it on your AD is that the lamp bolts are diagonal to one another, whereas the '35-'39 truck lamp had bolts in a straight vertical line. Check it out. If you can't find one, let me know and I will post a photo of mine.
Mike
