It's been a very slow day at work so I've been browsing T-34 data on the internet.
It seems to me that we're probably underselling the gun on the T-34/76. The difference in the way German and Russian tests measure penetration makes the paper numbers of the 76.2mm F-34 1942 L/41.2 seem less than they were when compared to the paper numbers of the German guns.
While I know Russian sources can be, um, biased, here is a quote from V. A. Malyshev in 1943:
"Enemy tanks opened fire on ours at distances of up to 1,500 metres, while our 76mm tank guns could destroy "Tigers" and "Panthers" at distances of only 500-600 metres. Imagine the enemy has a kilometer and a half in his hands, while we have only half a kilometer. A more powerful gun needs to be put in the T-34 quickly."
Looking at the data is seems that the T-34/76 (43) is not so different from a T-34/76 in 1941 or 1942 and so is quite usable in scenarios for those years. In 1941 and 1942 it would be a very formidable tank, but to reflect this we need a Panzer IV D.
Against the Panzer IV H the T-34/76 will be at a disadvantage, but less so, I think, than the M4A3 (75mm) Sherman. The front armor is only 47mm thick, but it is at an impressive 60° angle from vertical, which gives a straight on impact angle of only 30°. Any angle added from a shot not coming from directly ahead of the tank only adds to this. This will only be of marginal use against the the powerful 75mm KwK 40 L/48 gun on the Panzer IV H, it will be significantly better against future tanks from earlier periods or the 75mm M3 L/40 on the M4A3 Sherman.
The slope of the rear armor and the thicker rear hull and rear turret armor will probably make the T-34/76 indisquishable from the Tiger I when looked at from an M8's perspective. The M8 relies on punching out the Panzer IV H's turret from the rear and then repeated blows to the rear and side hull to kill it. It is likely that these hits will have no effect on the T-34/76.
The 20mm of deck armor will probably make the T-34/76 unkillable by aircraft guns other than the Il-2's 23mm and Hurrican Mk IID's 40mm cannons. Future additions such as the Ju-87G and Hs129 will also be capable of knocking it out with guns. All American aircraft however will rely on bombs and rockets. All current German and Japanese aircraft will need to rely on bombs, only the Hs129, Ju87G and Ki-102 really offering a chance of changing that.
As to the particular model we're getting, I'd say it is a T-34/76D with a welded turret and no commander's cupola. There seem to have been only 100 T-34/76Fs with the cast turret and no commander's cuppola produced before all production shifted to the T-34/85.
Here's a quick rundown on T-34/76 variants:
T-34/76A, Model 40: First models had 2 man turret that didn't provide vision devices or a cupola for the commander. Had L/30.3 Model 1938 tank gun mounted in a mount shaped like a pigs head. The first 115 vehicles had rear MGs installed. Had solid rubber tires around disc wheels.
T-34/76B, Model 41: Had rolled plate turret with a L/40 gun installed in an angular gun cradle. Late models had all steel wheels and a cast turret. 28 tons.
T-34/76C, Model 42: Larger turret with 2 roof hatches. Had improved tracks, vision, and armor for the hull MG. 30 tons. Driver had protecting visor for window. Hull MG is mounted in ball mantlet.
T-34/76D: Hexagonal turret and wider mantlet, plus external jettisonable fuel tanks. Thicker armor up to 70 mm. 30.9 tons. Two hatch covers in top of turret, that when open, led to it being nicknamed "Mickey Mouse" by German soldiers.
T-34/76E: Cupola added to turret and all welded construction.
T-34/76F: Cast turret with no cupola, 5 speed gear. Only 100 built as production switched to T-34/85.
