The following images I snagged with screen capture from a US govt. film made prior to first mission:
note B-25 in background:
B-29-40-BW 42-24592 73rd Wing, 497th Bomb Group, 869th Squadron.
One for Jack:
B-29-15-MO 42-65222 879thBS 499thBG
(edited to add serial numbers for future searches)