In Normandy, at such times as 'jabos' wre not available, a five unit Sherman Platoon would race to get to the rear of the Tiger or Panther to hit it in the rear where, allegedly, armor was thinnest.
No, I agree, I don't think just upgunning and retrackuing the Super Shermans alone beat the Sov Bloc Tanks in the Six day war.
What is clear is that a WWII issue unimpoved Sherman, despite the skill of the crews, would have had a very tough time against T-54 et al,
Regardless, as you say, the Six day war saw the capture of thousand of T-55's, for example, and upgunned in turn to be called the "Ti-67".
The Israelis do not seem to throw such vehicles away, but I don't know where they are.
"All Enlightenment Gratefully Accepted"