SU-76i

Quoting from [The Online Tank Museum]:
 * "The SU-76i was built or re-built by the Soviets because, while speeding up their huge production of tanks, they still faced shortages in certain areas. Furthermore, the original SU-76 model had several flaws. They were unreliable and not a pleasure to drive. During the fall of Stalingrad, the Soviets had captured several StuG and Panzer III tank chassis in relatively good condition. With the thought of rearming them with bigger Soviet guns, they were shipped back to factory 37 at Sverdlovsk."

Quoting from wikipedia:
 * "The SU-76i (the "i" standing for "Inostrannaya", or "Foreign" in Russian), first designed and fielded in 1943, was based on captured stocks of German Panzer III and StuG III chassis, a large quantity coming from defeated German troops after the Battle of Stalingrad that year."

This model of the SU-76i was modeled by Aemi1970. It includes a moving gun and hatches.