Remember these things were more akin to locomotives than assembly line Shermans, so there's always a steps along the way when things were introduced, some changes were to improve performance, some due to limitations in raw materials.

Plus they were prized equipment, recovered and refurbished whenever possible in anyway possible, just look at the variety of hulls used in the few Storms built.

All that said, the castle-like cupola was hated by the tankers since it was a natural shot trap and tended to break off when hit, frequently with the commander's head.

Early turrets on late hulls or visa versa probably isn't that rare considering. Initial construction time can be pinpointed by certain things: gun sights, escape hatches, s mines, close proximity weapons, loader's vision port, turret roof thickness, air cleaners, tool stowage, track hangers, road wheel type and config, headlights, track guards, etc. But once in the field, that's all out the window. A early survivor until Normandy may have picked up a host of motor pool add ons to keep it moving. Two broken tanks equal one working.