At idle speeds, foot on the brake, less than 1/2". In D, brakes held strongly, engine revved to 1500, less than 1".
Front center (mechanically restricted grease filled) motor mount. Best done up on a lift with jacks and patience, much interference removed.
If you regularly exercise the car as it should be, consider a set of Ranger's Rods. Out of production but easily fabricated. Google "cadillac forums deville ranger's rods" or "cadillac forums deville engine torque struts".