[MOTORHEAD]

The Switch assy itself should not bolt to the hub, but to the
steering column. If its a self-canceling turn signal, a canceling
device would bolt to the hub. Not having the device in my hands
I cant say exactly how this switch is set-up, but the picture you
posted looks like an early VW unit, which I believe is what was
used on the original Cobras. It may or may not be the correct
one to use on your Shell Valley, it all depends on what steering
column you're using. Call Enzo at Finish Line. He can tell you if
the switch he sells will fit the column in your car.
Good Hunting !!
Ted R.