I've seen 2 different styles of mounts on Brown 16 headlamps. One type the set screw is inside and screws out. The other the set screw is external and screws in from the rear. Why the difference from the same manufacturer? Different years 13 and 14 like the horn brackets?
The outside set screws are more common.
There are also differences in the shape of the mounting brackets on E & J 666 lights. Which preceded the other is a moot point.
Allan from down under.