Despite being mangled it does indeed look like a German 10.5cm leFH 18.
The T-34 is a fairly late production m1941. It has the final drivers hatch, the m1940/m1941 turret but no external shield on the BMG. There is no consensus of the model naming but sometimes that model is referred to as the m1941/1942. By that convention what ASL calls a m1943 is called a m1942 and the m1943 is the same as the m1942 but with a cupola. I doubt that the troops referred to them differently, if at all, other than slab-sided (m1941) or hexnut (ASL m1943) turrets. As usual with wartime production individual components would be used regardless of whether they were "right". You could have a case where a batch with the latest bits were followed by a batch with older bits as a new set would be stacked over old stuff and used first.