The driver, Mac, was a hefty guy. Even without his left torso, he still weighs over 200 pounds. I think the turret crew are trying to keep everyone else alive while the radio/bow gunner, Donald, cuts Mac into smaller (more easily lifted) chunks with his pocket knife.
Once Mac is out of the way, Donald will take over driving.
Uh oh. Donald's knife just snagged on a bit of tendon, and closed on his knuckles.
This might take a while.