The cranks come from the same forging but more mass is removed for a 2.5L crank during balancing due to the smaller (i.e. lighter) 2.5L piston & rod assembly. I suppose a crank shop could add weight to return the 2.5L crank to the 3.0L specification. Adding weight is always a risky thing to do though. If it ever comes loose, there will be hell to pay.
