99-05 F-SuperDuty Rear Suspension Lean: This applies to rear suspension lean only. The truck needs to be parked on a level surface with no load (or at least loaded evenly) and all tires inflated evenly. Inspect for spring damage or shackle bushing wear. Measure vertically from the lowest point of the wheel rim (not from the ground) to the wheel lip. If the measurment is within 3/5" from side to side, no action is required. If the measurement is greater than 3/4", measure the gap from the top of the axle to the rebound bumper bracket. If this measurment is within 3/4", inspect the body mounts and have the frame checked. If the measurement is between 3/4-1", install shim 3C3Z-5A300-AA on the low side, between the spring spacer and spring seat. If the measurement is between 1-1.75", install shim 5C3Z-5742-AA on the low side. If the measurement is greater than 2", replace the spring. Install longer U-bolts if necessary. TSB 04-23-6
