It appears that simply connecting (soldering) the new & more closely spaced lead in track’s outer rail commons to the metal base of the transfer table does this. From the photo below showing Lionel’s supplied track clips to hook up the lead in track’s commons at their standard location, it seems common AC runs through the table base itself, shown on an extension piece in this picture… and hot center rail power is supplied by the center rail of the moving ‘bridge’. I’ve read about it being done, and have viewed pictures of #350’s having closer track spacing than the standard 5.25 inches, but have found nothing that explains how the modified electrical connections are made.
Thanks in advance for any shared knowledge!
Tom