The SU-76M was the main production variant of the SU-76 type assault gun. It mounted the world famous Soviet ZiS-3 Anti-tank gun on a converted T-70 tank hull and a lightly armored rear mounted casemate. It was light so had excellent mobility being able to cross terrain that other tanks and TD's couldn't. The gun was effective against the lighter German tanks though needed to target the flanks of heavier German armor. It fired a good range of different projectiles making it an effective multipurpose vehicle. It even could elevate the gun high enough that it could serve in the indirect fire support role though it's small caliber gun was less effective than heavy artillery. It was the second most produced Russian vehicle of the war behind the T-34 and it's service life lasted till well after the war.
This is the tier II Russian Tank destroyer. It does lower damage than the Marder II, though not by much, and is a hair slower than the T48 GMC and has less view range and health but where this makes it up is in the turn rate. It is hard to get circled in this tank making it so you can support your team better since you can move up closer without the typical TD fear of being circled. It is still a better idea to stay back and use the view range advantage over tanks since they have more armor.