Why would anyone use the 9040C? The 9040B sits at a .3 br (doesn’t really matter, pretty much face the same tanks), is lighter, better turret speed, and more ammo. Why would I play the 9040C? For the 30mm more pen at 10m?
Significantly better angled pen, better armor to resist low-caliber munitions.
Better stabilization, 9040 has a good mobility and with a limitation on 9040B for around 40 km/h in a vehicle that you need to always be on the move, it’s quite unreliable and a clear reason, along with armor, for this BR differences.
They have the same stabilizer, you’re thinking the 9040A Bill II which has a 30km stabilizer. The 9040B is better for mobility alone which is vital for positioning with LT’s at top tier. Though very nap dependant