Van's,
If you can find a taxi sheet from the bomb group your Grandfather flew with it will have the pilot, airplane number and position in the formation. My Dad's group the 391st bomb group has the planes and their numbers and nose art name listed on a page. I looked at the taxi sheets and could deternine which planes he flew for what mission. The mission objectives are also listed. Pretty cool stuff.
Good luck!
Swoose<S>