I just took another look at the TOW manual, and it seems to give an official word on the matter:
Damage Calculations
The following factors are taken into consideration in the game whenever
damage is calculated for various types of objects: ballistics (every
weapon in the game has its own ballistics parameters), hit angles, armor at
the hit location, shell inertia, high-explosive effect, detonation, blast pressure
wave, secondary effects, ricochets, anti-HEAT screens, ammo detonation,
and inflammation. The following systems may be disabled:
o Chassis:
o Transmission;
o Engine;
o Wheel or tracks
o Turret;
o Guns;
o Machine guns;
o Crew