This mount uses the two bolts that are used to mount the from truck to the board. Bolts may need to be longer if they are too short so engage the nylock nut.
Clamping bar is 1.175 inches in diameter.
Through holes are .300 inches and counter bore is .510 inches.
Headlamp shown works really well; It's 2000 Lumens, rechargeable and doesn't
have an external battery pack.
More info on the headlamp can be found
here on amazon.
Now Leeloo can run at night!