That serial has the following info in my records:
41-2666 Construction number 2478
Boeing B-17E Fortress
Assigned: 43rd BG, 65th BS, "Lucy"
Notes:flown on mission which earned Jay Zeamer and Joseph Sarnoski the Medal of Honor Jun 16, 1943, Bougainville.
Now, was that B-17 later converted to a YB-40 escort gunship? That's a difficult question. I am trying to track down serial numbers of YB-40s.