Shermans were not well armored---downside---and compared to a Tiger or Panther were under-gunned. But their equivalent, the Mark series, we were fine with that.
Exactly. They did not have to go toe to toe with the best German tanks. They just flanked them and by the time the Panzers caught up half of them were down for maintenance anyway. The other half got blasted from the air while the Sherman’s drove over the horizon.
“120mm guns were introduced that made the Sherman the equal of a Tiger 1.”
The Brits up-gunned their Shermans with 76.2mm guns to create the “Firefly” which with better ammo could take out a Tiger II at 1000+ yards.
There were SPGs and Tank Destroyer variants with 90mm, 105mm and 155mm guns, but no WWII production Sherman ever had a 120mm gun to my knowledge and brief internet search. What various armies around the world did with Shermans after the war I cannot be held responsible for.
If you can point me to some info I have missed I will stand corrected.