Zone Offroad 2.5-Inch Leaf Spring Leveling Kit | 5-Leaf Progressive Mini-Pack | Adjustable Track Bar Included | No Rear Lift | 33" Tire Clearance | 1999–2004 Ford F-250 / F-350 Super Duty 4WD | SKU: ZONF4

⚠️ PRE-3/1/1999 EXCLUSION: Trucks manufactured before March 1, 1999 do NOT fit — the early 1999 production run used a different 5/8" track bar bolt head size.

⚠️ U-BOLT VARIANCE: Check your front axle U-bolts before installation — round vs. squared-corner U-bolts are two different configurations on this platform.

Verified Fitment

Does NOT fit:

• Ford F-250 / F-350 Super Duty built before March 1, 1999 — early 1999 production used a 5/8" track bar bolt head size that is incompatible with this kit's adjustable track bar
• 2005 and newer Ford F-250 / F-350 Super Duty — different front suspension architecture; leaf spring leveling kits are platform-specific
• 2WD / RWD Super Duty (1999–2004) — solid front axle with leaf springs is 4WD-specific
• Ford F-450 / F-550 (1999–2004) — not confirmed for this kit
• Ford F-150 (any year) — different platform

Early 1999 production cut-off: The 1999 Super Duty went into production during the 1999 calendar year. Trucks built before March 1, 1999 used a different track bar bolt head diameter. Zone's adjustable track bar in this kit is not compatible with those early units. To confirm your build date, check the door jamb sticker — it lists the manufacture date. If it reads before 3/1/1999, this kit does not fit.

Component Specifications

Why leaf spring mini-packs instead of a spacer: The 1999–2004 Super Duty uses a solid front axle with leaf spring front suspension — completely different from the 2011–2016 Super Duty's independent coil-spring front. Spacers cannot be added to a leaf spring suspension to achieve lift. Instead, Zone's 5-leaf progressive mini-pack replaces the existing leaf spring pack with a purpose-built replacement rated to lift the front 2.5 inches while maintaining load-carrying capacity. The progressive rate design means the spring softens ride over minor bumps but stiffens progressively under load — preserving both daily drivability and work truck payload functionality.

Why the adjustable track bar is critical: On the solid-axle 1999–2004 Super Duty, the front track bar connects the axle housing to the frame and controls lateral axle positioning. When the front of the truck is raised with new leaf springs, the track bar geometry shifts — pulling the front axle off-center laterally. Without an adjustable track bar to compensate, the front axle walks to one side, causing alignment issues and uneven tire wear. The adjustable track bar included in this kit allows the installer to re-center the axle under the lifted truck and restore correct lateral positioning.

What Is and Is NOT Included

No rear lift included: This is a front-only leveling system. For operators who also want rear leveling, Zone offers separate rear lift block options (leaf spring blocks with 5/8" pins) for this platform. The ZONF4 addresses only the nose-down factory rake.

Critical Compatibility

Three checks before ordering this SKU:

1. Build date after March 1, 1999. Check the door jamb manufacture date sticker. Pre-3/1/1999 trucks used a different track bar bolt head size. If the sticker shows before March 1, 1999, this kit does not fit.
2. 4WD drivetrain. The solid front axle with leaf spring suspension is a 4WD-specific configuration on this generation Super Duty.
3. U-bolt configuration. This is not a fit/no-fit issue — both U-bolt configurations are accommodated — but the buyer must identify which style their truck has (round radius vs. square-corner) before beginning installation. The correct U-bolts from the kit must be selected for the axle configuration.

Solid front axle vs. coil-spring IFS: The 1999–2004 Super Duty uses a solid front axle — both axle shafts connect to a single housing that spans the full front width. This is a fundamentally different architecture from the 2011–2016 Super Duty's independent front suspension. The leaf spring mini-pack in this kit is engineered specifically for the solid axle's spring perch geometry and cannot be used on a coil-spring independent front suspension.

Installation Notes

Skill level: Intermediate — leaf spring replacement requires spring removal and reinstallation with proper tools. More involved than a coil spacer leveling kit. Professional installation recommended.

Tools required: Floor jack and rated stands, spring clamps, basic socket set and torque wrench. No cutting or welding required.

U-bolt identification — required before installation: Before beginning, look at the front axle U-bolts. If they have a curved/round radius where they wrap around the axle housing, you have round U-bolts. If the corners are squared off where they wrap around the axle, you have square U-bolts. Select the appropriate U-bolts from the kit hardware before starting.

Installation sequence:

1. Safely lift and support the vehicle with the front suspension at full droop.
2. Remove factory front leaf spring pack per Zone's installation instructions.
3. Install Zone's 5-leaf progressive mini-pack at the same spring perch mounting points.
4. Install the appropriate U-bolts (round or square-corner per your axle) and torque to specification.
5. Install the adjustable front track bar, replacing the factory track bar. Set initial adjustment length to approximately the factory length.
6. Lower the vehicle to ride height.
7. Verify front axle centering — confirm equal distance from the tire to the frame/fender on both sides. Adjust track bar length until axle is centered.
8. Fully torque track bar hardware at ride height.
9. Schedule and complete a front-end alignment.

Alignment mandatory: Even with the adjustable track bar re-centering the axle, a professional alignment is required to verify and set caster, camber, and toe.

Common Questions

Does my 1999 Super Duty fit this kit?
It depends on build date. Check your door jamb sticker for the manufacture date. If it shows before March 1, 1999, this kit does not fit — the early 1999 production run used a different track bar bolt head size. If it shows March 1, 1999 or later, you're good.

Why does this kit include a track bar? The ZONF45 (2011–2016 Super Duty) didn't.
Different suspension architectures. The 2011–2016 Super Duty uses independent front suspension with coil springs — the front axle centering is managed differently. The 1999–2004 Super Duty uses a solid front axle with leaf springs where the track bar is the primary lateral locator for the entire front axle housing. When you raise the front with new leaf springs, the track bar geometry shifts and pulls the axle off-center — you need an adjustable track bar to bring it back to center. Without it, the truck won't align correctly and will exhibit pull.

What's the difference between round and square U-bolts?
The front axle on the 1999–2004 Super Duty used two different U-bolt shapes during production. Round U-bolts have a continuous curved radius where they wrap around the axle. Square-corner U-bolts have a flat bottom with squared corners. The correct type must match your axle housing profile for a secure, flush fit. Look at your existing U-bolts — or look at the bottom of the axle housing itself — to identify which style you have.

Does this raise the rear of the truck too?
No — the ZONF4 is a front-only leveling system. The 5-leaf mini-pack raises the front 2.5 inches to eliminate the factory nose-down rake. If you want rear lift to match, Zone offers separate rear lift blocks for this platform.

Will this maintain my truck's towing capacity?
Yes — the progressive rate mini-pack is specifically designed for work truck applications. The progressive leaf design provides a softer rate for light loads and stiffens under heavy loads, maintaining the truck's load-carrying geometry.

The Obsidian Take

The ZONF4 is for the owner of a 1999–2004 solid-axle Super Duty who wants to eliminate the factory nose-down rake and run 33-inch tires without going to a full suspension lift. The 5-leaf progressive mini-pack is the correct engineering approach for this platform — not a spacer, not a block under the spring. A purpose-built replacement leaf pack that lifts the front 2.5 inches while preserving load-carrying function through the progressive rate design.

The adjustable track bar inclusion is not optional equipment — it's an engineering requirement for a solid-axle lift. Raising the front of a solid-axle truck with new springs shifts the track bar geometry and walks the axle off-center. The adjustable track bar is how you bring it back. Any lift on this platform without an adjustable track bar produces a misaligned front axle and uneven tire wear. Zone builds it into the kit because it's not a separate upgrade — it's part of a complete correct installation.

The U-bolt check is the one pre-installation step that catches people off guard. It takes 30 seconds to look under the truck and identify whether you have round or square-corner U-bolts. Do it before installation day — both are accommodated in the kit hardware, but you need to select the right ones before you start.

For operators who work their Super Duty — towing, hauling, camper use — the progressive rate spring design is the practical advantage over a simpler spring spacer approach. The spring stiffens under load rather than letting the lifted front compress back toward stock height when the truck is loaded. The leveled stance holds under realistic work truck loads.

This SKU is for: 1999–2004 Ford F-250 / F-350 Super Duty 4WD owners (built after 3/1/1999) who want 2.5 inches of front leveling with a progressive-rate leaf spring replacement, adjustable track bar for axle centering, and clearance for up to 33-inch tires without a rear lift.

This SKU is NOT for: Early 1999 production Super Duty owners (built before 3/1/1999 — track bar incompatible), 2WD Super Duty owners, 2005 and newer Super Duty owners (different suspension — different kit required), anyone expecting rear lift (front-only leveling system), or F-450/F-550 owners without prior verification.

Manufacturer Data Disclaimer
Product specifications, fitment data, and feature details are sourced from Zone Offroad manufacturer documentation and verified third-party technical references current at the time of publication. Zone Offroad reserves the right to modify product specifications without notice. Confirm build date (after 3/1/1999), 4WD drivetrain, and front U-bolt configuration before ordering. OFAS is not responsible for incompatibility resulting from pre-3/1/1999 build date applications, 2WD configurations, or post-2004 generation misidentification.

Prop 65 Warning
⚠ WARNING: This product can expose you to chemicals including lead and lead compounds, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, go to www.p65warnings.ca.gov.

Non-Returnable Notice
This item is non-returnable once installed. Verify 1999–2004 model year, build date after 3/1/1999, and 4WD drivetrain before ordering. Questions before ordering? Text (469) 407-7538.