The AA tanks (Cheetah and Tigris) are great and don't need much changing, however there is one thing that could be changed with the way the AUTO ranging works (visually).

The way it is now, the bullets come out of the cannon barrels at odd angles (to account for drop/lead etc). Functionally it works great. But it looks a little odd if seen from up close or the gunner's view.
A better thing to do would be to have a commander-like camera setup which sits on top of the turret.
The cannons would be normally locked to the gunner's camera view. When the zeroing of the guns was increased, the guns would increase in angle as compared to the gunner's line of sight (as would be expected in real life).

The interesting stuff begins when the Auto-ranging is used:
When the gunner locks onto a target, the turret swivels and raises independently of the gunner camera's line of sight. This way, instead of the bullets coming out of the barrels at odd angles, the barrels swivel to compensate for the drop and lead. Works just as well, looks amazing.