My latest Suburban furnace the fan/ motor is slightly out of balance. I can definitely feel it in the furnace when it is running. It has not proven to be noisy (yet). Given the speed and small amount of rotating mass, I can safely conclude they didn't shoot for the moon on the quality of the fan and motor.
If the fan/motor is exciting rattles and noises, I'd check the root cause: balance. I don't know if these can easily be balanced, or a replacement is in order. Anything you could do to cut down on vibration would be beneficial.