How modernization changes a Sherman comparison

Where should the definition of a Second World War tank end when the vehicle has been extensively modernized?

An extensively rebuilt Israeli Sherman is a poor proxy for an original wartime Sherman because later modifications substantially changed its capabilities.

Long service does not mean a vehicle retains its original combat capabilities. Israel's extensively modified Shermans raise the question of where a comparison with a Second World War tank should stop. The particular version is tentatively identified as the M51, and its large replacement gun is central to the example. The panel compares the extent of those changes with a much later tank, while briefly disputing whether the rebuilt vehicle should be called a tank or a tank destroyer.