I' ve read that, during World War II, it was a common event that a tank, having received an impact from a round unable to penetrate its armour, remained inactive in the field of battle for a while or indefinitely. All the kinetic energy from the impacting round was absorbed instantly by the part of armor affected, that transmits this energy as a massive shock wave to all the tank. The entire vehicle can act as a big resonance box (not sure if this a correct English term)
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The result could be simply a confused crew their ears aching. But other effects like the loss of consciousness or dead were possible, depending of the proximity of the crew member to the impact zone.
A RPG from Spain called "Comandos de guerra", has a special rule covering this. Basically, if the vehicle suffers the loss of armor points due to the impact of a round, the crew must make a constitution roll to avoid loss consciousness, with a catastrophic failure involving death. The difficulty of the check was adjusted by the proximity to the impact zone.
In T2K (v2.2) the crew members can suffer damage either with a "minor" or with a "major damage" result on the Vehicle Damage Table. And the rules take in to account the position of the crew member. So perhaps the only adjustment necessary may be the CON check of the all the crew members, DIFFICULT for those who has suffered damage in the Vehicle Damage Table and AVERAGE for the others. With a failure, apply 1d6 damage points to the head. Catastrophic failure doubles damage. Perhaps a good option would be to limit this effect only to large caliber guns.