Can anyone give me an idea about crew compliment/positions on USAAF B-24s D, J & H variants in say 1944, 8th Airforce.

Looking at some crew manifests from the era there seems to be wide variations in crewing, some appearing to have dedicated front gunners, some combined nav/front gunners, some with ball turret some not on same type....list goes on.

I'm assuming some forced flexibility due to wartime conditions (losses, injuries etc) but the B-24 manifests certainly seem more random than B-17 crew lists from the same time.

Thanks in advance for your help/thoughts.