The Israelis never had any uparmored M4A3E8. In fact the vast majority of Israeli Shermans were M4A1 cast hull types. Many of course had HVSS, but HVSS does not mean solely M4A3E8. The M51 Isherman the one with the French 105mm gun were all cast hull HVSS types with no extra armor. For what its worth your friend is entirely mistaken in this area.
As for up armor kits the army did make a bunch of new glacis applique plates for M4A3 thype hulls but from what I know they were all one inch thick plates. The only curved side plates for the turret were again one inch thick plates to be mounted on the right side of some early Sherman 75mm gun turrets. This was needed to cover up a thin armor area because the cast armor was ground away from the inside to clear a new turret traverse gear. Later 75mm turrets incorporated thicker casting in this area and you can see a tiny overhang in the right front turret area.
The army also had a kit to improve armor on T23 style turrets. This consisted of a flat one inch thick plate assemmbly that was bolted/welded to the front quarters of the turrets. I have never seen or heard of any army kit to up armor the mantlet of a T23 turret.
But whatever our disagreements there certainly were official and unoffical attempts to uparmor the Sherman in late 1944 early 1945. The expedient Jumbos were a part of this. But of course they were exceeedingly rare and came in too late to have any real effect. The Sherman was still very much outclassed however by the Panther.
The Pershing largely closed the gap but even the US army considered it inferior to Panther, go figure. Thats from Hunnicuts Pershing book.
T28/T95 are pretty damn cool, the also had an "assault" tank named the Tortise, it mounted a 32lbr gun.
It really wasnt like mouse, mouse was inteded as a, gasp, combat tank whereas T28 and Tortise were fortress assault tanks.
Anyyway any of these huge supertanks were wasteful beyond belief and would have been killed by airstikes where possible.
BTW the Garmans drew up plans for a "tank" powered by four U-Boot engines that mounted turrets from a Cruiser or Pocket Battleship.
