According to this article, the plane itself was found while researching Lt. Col. John Donalson, who was credited with piloting the lead aircraft during the invasion.

It also provides a reason why this plane was selected:

"Donalson's plane was in the lead partly because it was equipped with an early form of radar that homed in on electronic beacons set up on the French coast by a small group of paratroopers in "pathfinder" aircraft, Scales said. Some mountings of that electronic system remain on the C-47's fuselage."

https://www.nbcnews.com/news/military/d-day-anniversary-cere...