I'll give this script a try if nobody else wants to. But the chance of the tank being destroyed is almost impossible. If you plan to use a standard frag grenade, it would kill the turret crew and possibley injure the driver (depending on vehicle design). It would also damage internal turret equipment such as hoses, wiring, control panels, electronics, and any other sensitive components in the turret that are exposed. But in most modern MBT's the shells are stored in a protective bustle, so they would not detonate. Remember that this is based on the player using a frag grenade, inciendary grenades might have a more likely chance of ammo detonation. But for more realism, I would use the frag grenade method, since those are the grenades used in the game without need of an addon.
I can write this script for use on MBT's, but using it on a vehicle like an APC or IFV might not be realistic. I will write a simple script that will kill the turret crew but not driver, and will add those animations. If someone else wants to write a larger version that will check vehicle class, that would work for realism in APC's. If a frag was dropped down the turret of say a BMP, the blast would have chance of wounding everyone within the vehicle, including passengers in rear. If the script was able to detect the vehicle class, tank compared to apc, then it can choose from one of two scripts. Tank class would just kill gunner and commander, APC class would kill gunner and commander, and have random chance of killing or injuring driver and passengers. APC script(s) would take a little more work, but would make the stuff more interesting.
Does this sound like what you are wanting? If so, I'll give the tank version of this script a try. Might take a day or so, I'll try to get it to look good.