Idealized training days - M7 Priest

According to his own handwriting in a service journal, my wife's grandfather spent three summer days of 1944, somewhere in England, training on or around an M7 Priest. He shipped to the main European theatre shortly after. He survived the war and lived on to play with his grandchildren.
The project plan is an overly ideal, stylized, vignette of one of those training days. Primary will be the Academy M7. Truck crew members with full pants & sleeves will be adopted as instructors or trainees.