The M44A3 is the result of an internal struggle between two Unity departments: Ordnance and the Armored Board. Ordnance had given the Armored Board the M44A2 Spartan, which was a good vehicle on paper, but the biggest complaint was the small turret on a MBTs hull, which could take a much bigger and more capable turret. The second complain was the gun. While extremely effective for its caliber, the standard Paternian 8x8 IFV as well as its tracked Dragon IFV was armed with a 30mm revolver cannon. Unity reached out, and the nation of Midgardia answered with a larger turret, capable of mounting the high-velocity 90mm Gun M15 in an autoloading mount, which is set to replace the standard M53 Stryker. Back on track, the M44A3 gets a major upgrade in two major areas. The subcontractor Atlas Engineering Corporation had developed a new high-velocity 35mm cannon named M191. With a few tweaks, this became the M191A1, which looks like an up sized M17A1. The A3s secondary weapon is four R-15 Sapper ATGMs, capable of both direct and top-attack modes. The Turret on the A3 is just as heavily armored as the hull, making use of Archangel VI composite. The turret includes two-axis stabilization (not represented in SP). The M44A3 replaces all previous variants of the Spartan.
Credit to MadBomber for giving me the turret and helping scale a few parts