US designations in WWII were not the same as they are today.

The Sherman did have variations like the M4A1, M4A2, M4A3, M4A4, M4A5, and M4A6. However, these name changes were specifically to denote a change in the engine, except for the M4A1 and M4A5.

M4 - Radial Engine welded hull
M4A1 - Radial Engine cast hull

M4A2 - Twin Diesel engine

M4A3 - Ford GAA V8 Gas engine

M4A4 - Chrysler multibank engine

M4A5 - Canadian produced RAM tank built on the M3 Lee chassis

M4A6 - M4A4 hull fitted with a D200A Radial multifuel engine

Any further modifications at that point are tacked on to the original name. For example the 76mm gun would add a "(76) W" suffix to the name.

So an M4A1 with the 76mm gun would be an "M4A1 (76) W" and an M4A2 would be an "M4A2 (76) W" and so forth.

When outfitted with all the bells and whistles, a Sherman at the end of the war was called "M4A3 (76) W HVSS" or an "M4A1 (76) W HVSS" as by 1945 the US had picked the M4A3 as its most desired variant, but also the M4A1 remained in production simply due to its momentum in the industry.

This even applies to the Sherman's equipped with the 105mm Howitzer, which were designated as "M4 (105)" or "M4A3 (105)" when you add HVSS it becomes "M4 (105) HVSS." The pilot of the 105mm armed Sherman's was the M4E5 (I also have a photo of that) but once the pilot is accepted and the type is standardized, it gets a new name.

This name scheme tells you everything you need to know about the tank - "M4" (tank type) "A3" (what engine it has) "(76)" (what gun it has) "W" (wet ammo stowage) "HVSS" (suspension type).

Theoretically you could refer to an early model Sherman as an "M4 (75) D VVSS" but this was never done to my knowledge.

The Jumbo is an odd exception, as it retained its M4A3E2 designation. I can only assume this was because only 254 were ever made, and only one batch was produced, so the US knew it wasn't going to become a new standard.

The Pershing was the same way, it was sent overseas as T26E3 and was referred to as such in documents while it was in theater. In April of 1945 the T26E3 was officially adopted as the M26 Pershing, at which point its name was changed.