At Normandy, tank ace, Major Michael Wittmann commanded a group of seven tanks. This was probably a unit that had been decimated by casualties. Even so, my understanding is that an officer of Wittmann's rank might command a unit of 9-15 tanks at full strength.
Given the above, what might be the ranks of the five crewman of an individual tank? My guess is that the most senior would be a first or second lieutenant, or at least a senior non-com, the most junior might be a "buck" private, with numbers two, three, and four being of "intermediate" ranks. How close is this guess to actual ranks in known units?