In the December 2007 issue of Smithsonian magazine is an article “Ike at D-Day”, an excerpt from Michael Korda’s biography of Eisenhower. In the description of invasion-eve preparations appears this:
I’m not sure how, but it ought to be possible to check on this (has anyone done so?). Some few of those bombers survive today, and it’s quite fashionable among the warbird crowd to fit them with every sort of authentic accessory - I have seen P-51 fighters with wing guns that looked factory-new, complete with loading diagrams.