I seriously doubt anyone would be silly enough to internally balance an OE cast crank. I know I probably wouldn't do it, even if the customer wanted it.
It would be an incredible waste of money. I can find better places to spend money than to internally balance a crank like that, especially if they already had a damper and torque converter.
But, I've been doing this long enough to know that stranger things happen. But I doubt this is a cast crank.
BTW, back in the day I've seen engines balanced with a weighted damper on the front just for the claimed better dampening characteristics.