Parts ID help please. USAAF Camera mount ??

Can anyone help with a part that I recently acquired.
Its obviously some sort of camera mount but can anyone identify what type of camera would be used and also what type of aircraft it was fitted to.
is it a WWII item or a post war item. Has anyone got a plan/picture of the item in situ ?
Lots of questions I know but I really have no idea.
Many thanks