tank - the two engines were mounted in tandem on the right hand side of the vehicle. The armoured roof over the gun compartment was removed to improve access, servicing of the weapon and ventilation. Testing of new self-propelled guns was carried out at the Gorohovets training ground in the midst of the Battle of Kursk. The SU-15 enjoyed the greatest success with the military, and it was recommended for serial production after some modifications. In July 1943, the SU-15 under the army designation SU-76M was adopted by the Red Army. After production resumed, GAZ and two factories in Kirov and Mytishchi produced 13,732 SU-76Ms; over 9,000 of the vehicles were built solely by GAZ. Mass production of the SU-76M ceased in the second half of 1945. In contemporary accounts SU-76Ms are often referred to in texts, public radio and TV broadcasting as SU-76s with the "M" omitted, due to their ubiquity in comparison with the original SU-76s. The SU-76 was the basis for the first Soviet tracked armoured anti-aircraft vehicle, the ZSU-37. Mass production of the ZSU-37 was continued after SU-76M production ceased. All SU-76Ms had been withdrawn from front-line service shortly after the war ended, although some were retained as training vehicles for T-34 crews as late as 1955. Variants OSA-76 Experimental model based on the T-60 tank chassis. SU-76 (factory designation SU-12) Based on a lengthened T-70 light tank chassis, with the inferior dual-engine arrangement of earlier T-70s. Only 560 were produced, and these were quickly withdrawn from front line service. Nearly all SPGs of this version had armored roof, but it caused ventilation issues and was often removed in field depots, SU-76M lacked roof from start. Combat mass 11,200 kg. SU-76M (factory designation SU-15) Main production model. SU-85A/SU-85B SU-76M armed with 85mm gun (D-5S/LB-2 respectively), prototype only. ZSU-37 Self-propelled anti-aircraft gun, based on the SU-76. In 1978, Institute 111 from Romania designed an armoured personnel carrier based on the SU-76 chassis, equipped with the TAB-71 turret. The vehicle entered service as the MLVM (, meaning "infantry fighting vehicle of vânători de munte"). Unrelated vehicles The unrelated 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 partially-modified vehicle was armed with