1999-2004 Superduty Rear Loadlifter 5000 Air Spring Kit (ALF57390)Restore the hauling confidence of your 1999 2004 Ford Super Duty with the Air Lift LoadLifter 5000 air spring kit. As these legendary trucks age, factory leaf springs can often fatigue under heavy loads; this kit provides up to 5,000 lbs. of load leveling capacity to bring your F 250 or F 350 back to a level, stable ride height. By installing these heavy duty air springs between your frame and rear axle, you eliminate the sag, trailer sway, and