Thanks Mike. Looks like I either have a rare version 4 or someone, for unknown reasons, expertly machined a version 3 (blank boss), because the the boss was been spot faced and tapped with a course thread. This came off a '67-'68 bike. Anyways, my bike's a true replica, so a version 1 (no boss) is going back on. I'll save your harness for a planned, highly modified, rider in the future that will use the front brake light option.
Merry Christmas all!