Ford 1999–2004 LoadLifter 5000 Helper Spring Kit | Air Lift 57390

Stop rear sag, trailer sway, and bottoming out on your 1999–2004 Super Duty. The Air Lift LoadLifter 5000 kit (part #57390) adds up to 5,000 lbs of adjustable rear load support so the truck stays level, stable, and in control whether you are towing a fifth-wheel, running a gooseneck, or hauling a heavy bed load. This under-frame kit is built specifically for 1999–2004 F-250/F-350 4WD pickups and works with factory leaf springs plus most side-mount fifth-wheel and in-bed hitch setups. Air pressure is fully adjustable from 5–100 PSI, so you can run a firm loaded ride on the highway and drop pressure for a smoother empty ride. Helper air springs work with the factory suspension so you keep stock ride height when empty and add support only when you need it.

Key features

• Up to 5,000 lbs of load-leveling capacity (never exceed the truck’s GVWR)
• Adjustable from 5–100 PSI for empty, partial, or max-load conditions
• 2-ply fabric-reinforced rubber bellows built like a tire
• Exclusive upper and lower roll plates protect the bags and help increase capacity
• Corrosion-proof nylon composite end caps that are steel-strong, lighter, and rust-free
• Under-frame, no-drill installation on most applications
• Quick-connect polymer air fittings with included air line and Schrader valve
• Works with most side-mount fifth-wheel and in-bed hitch systems
• Fits both single rear wheel (SRW) and dual rear wheel (DRW)
• Limited lifetime warranty

Fitment

• 1999–2004 Ford F-250 Super Duty 4WD
• 1999–2004 Ford F-350 Super Duty 4WD
• Compatible with 7.3 Powerstroke diesel and gas engines
• Rear axle / factory leaf springs

Does not fit 2WD models or cab & chassis trucks. Fits trucks with no fifth-wheel hitch and most side-mount fifth-wheel or gooseneck applications.

What’s in the box

• Pair of LoadLifter 5000 air springs
• Upper and lower roll plates
• Vehicle-specific mounting brackets and hardware
• Air line, fittings, and Schrader fill valve
• Illustrated installation manual

Notes & specs

• Compressor, in-cab gauges, and wireless controllers are not included
• Pair this kit with an Air Lift WirelessONE, LoadController, or similar onboard air system if you want to adjust pressure from the cab
• Brand/part number: Air Lift LoadLifter 5000 57390
• UPC: 729199573903
• Position: rear
• Capacity: up to 5,000 lbs
• Pressure range: 5–100 PSI
• Mount: under-frame
• Drilling: typically none
• Install time: about 1–2 hours
• Replacement spring: Air Lift 50201
• Kit weight: about 35 lbs
• Warranty: limited lifetime

Most 57390 kits bolt on with no frame drilling and install in roughly 1–2 hours with basic hand tools. Route the included air line to a convenient fill point at the bumper, bed, or license-plate area. Always set pressure for the load you are carrying and do not exceed the vehicle manufacturer’s GVWR. If your 1999–2004 Super Duty squats when you hook up a trailer or load the bed, the Air Lift 57390 LoadLifter 5000 kit is the vehicle-specific fix: 5,000 lbs of adjustable support, hitch-friendly under-frame mounting, and a lifetime warranty.