Some information I have found in the web:
In 1943 it was decided to use big storages of German tanks to convert them to assault guns designated SU-76i ("inostrannij" = foreign).
The modifications consisted of the removal of the turret and upper part of the hull in case of PzKpfwIII / PzKpfwIV and the superstructure in case of StugIII, while all other components remain unchanged. Modified vehicles were mounted with welded boxy superstructures (forward armor 35mm, side and rear armor 15-25mm) which housed 76.2mm F-34 or 76.2mm ZIS-5 tank gun and storage space for 98 rounds. SU-76i was operated by the crew of four, who had a submachineguns and a hand grenades for local defense. A driver used the unchanged German equipment, while other equipment was of Soviet origin. SU-76i weighted about 22t; it could travel at the maximum speed of 40km/h as the base tanks. 201 of such SPGs were built, including 20 command SU-76i.
In Augst 1943, 1902th SAP had 15 SU-76i and five SU-76. Also, 1901st SAP and 1903rd SAP were equipped by SU-76i.
This particular vehicle was supporting the 143rd Rifle Division during their advance on Sarny on January 11th of 1944. The SU-76i attempted to cross the frozen river but ice broke and it sunk with its crew. It was discovered in 1972, recovered, renovated and placed on display at Lenin Prospekt Memorial at Sarny:
|Source: The blueprints.com|
|This was the first attempt of building the superstructure.|
|I wasn´t pleased with this roof so I startet a second try:|
|end of day two|