I noticed it has been many years since you posted this originally. I have been 'googling' the 448th Bomb Group 713th Squadron and came across your post.
I have a list of crew 74-17 through crew 74-32 of the 713th Bomb Squadron.Your father's crew is listed as Crew 74-21.There were four other men connected to that crew.My husband felt they might have been the maintenance crew assigned.
Cpl Robert Prouty T/Sgt Ernest Lapko T/Sgt Markus A Schraacko Sgt Ernest H Stark
I have the men's service #s for the crew if you want those.