Wiring Question

["Robert Berning" <rob@berning.org>]

I have a 1972 MGB, ever since I bought the car it has a wire hanging under
the car.  The wire goes from the fuse box area under the hood, down by the
starter along the floor board under the car to the rear of the car.  The
wire bundle contains a green, green/white, and green/red wires .  Attached
is a wire clamp attached to a L-bracket.  I looked all around to find where
to mount the L-bracket but cannot find a place.
Can you help me out?

Thank you,
Robert Berning
rob@berning.org