Axiom Supply Stage 3 FOX 2.5" Performance Leveling System GM HD Truck 2500 / 3500 Silverado / Sierra 2001-2010

Fitment

The Axiom Supply Stage 3 FOX 2.5 Performance Leveling System is a complete front and rear suspension upgrade engineered specifically for the 2001-2010 GM HD truck platform, combining adjustable front ride height, corrected suspension geometry, increased wheel travel, and premium FOX 2.5 Performance Series shock control.

Chevrolet / GMC HD Trucks

Chevrolet Silverado 2500HD – 2001-2010

GMC Sierra 2500HD – 2001-2010

Chevrolet Silverado 3500 / 3500HD – 2001-2010

GMC Sierra 3500 / 3500HD – 2001-2010

Fitment Notes

Fits applicable 2WD and 4WD models.

Compatible with gas and Duramax diesel applications.

Fits both 2001-2007 Classic and 2007.5-2010 New Body Style GM HD trucks.

Provides up to 2" of adjustable front ride height.

Includes application-specific FOX 2.5 Performance Series IFP shocks:

Front: Axiom AX4074 / FOX 987-24-074 – designed for 0-2.5" front lift

Rear: Axiom AX4075 / FOX 987-24-075 – designed for 0-1" rear lift

The complete Stage 3 system is intended for trucks retaining approximately stock rear ride height through 1" of rear lift.

Compatible with factory rear suspension, mild rear block configurations, and airbag-assisted applications that remain within the intended rear shock operating range.

Designed around the factory upper control arm mounting locations.

Oversized tires may require additional wheel offset or spacers for adequate upper control arm clearance.

A professional alignment is required following installation.

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Features

Complete Stage 3 FOX 2.5 Suspension System – Combines Axiom Heavy-Duty Upper Control Arms, forged torsion leveling keys, Grade 12.9 ball joints, premium bushings, and a complete set of FOX 2.5 Performance Series IFP front and rear shocks into one integrated suspension package.

FOX 2.5 Performance Series Shocks – Includes four application-specific FOX 2.5 Performance Series shocks utilizing large-bore monotube architecture, vehicle-specific valving, and increased damping capacity for improved ride quality and suspension control both on and off-road.

Axiom AX4074 / FOX 987-24-074 Front Shocks – Specifically engineered for the front of the early GM HD platform with a 0-2.5" front ride-height range, making them ideally suited to the adjustable front leveling range of the Stage 3 system.

Axiom AX4075 / FOX 987-24-075 Rear Shocks – Specifically engineered for 0-1" rear ride-height applications, providing properly matched rear damping for stock-height, leveled, mildly blocked, and compatible airbag-assisted trucks.

Ride-Height Corrected Caster Geometry – Unlike many aftermarket upper control arms designed around a fixed amount of correction for one predetermined leveling height, the Axiom control arms feature caster correction engineered directly into the arm geometry, providing usable alignment range throughout varying front ride heights.

Large-Bore 2.5" FOX Shock Bodies – Increased piston area and fluid capacity provide greater damping authority and improved resistance to heat-related performance fade during towing, rough-road use, and extended suspension operation.

Internal Floating Piston Design – FOX IFP technology separates the shock oil from the high-pressure nitrogen gas charge, helping prevent aeration and maintain consistent damping performance under demanding conditions.

High-Flow Velocity-Sensitive Damping – FOX's damping system responds to shock shaft velocity to provide smooth control over smaller road imperfections while increasing damping authority during larger suspension movements.

Impact-Extruded 6061-T6 Aluminum Bodies – Lightweight aluminum construction efficiently transfers heat away from the shock oil while providing excellent corrosion resistance and long-term durability.

5/8" Hard Chrome Shock Shafts – Heavy-duty shaft construction provides the strength and durability required for GM HD trucks, larger tires, towing loads, and demanding terrain.

True Double-Shear Control Arm Construction – Built from identical upper and lower 3/16" steel plates that are precision laser cut and hand welded into a single rigid structure. Supporting the ball joint mounting area from both sides distributes suspension loads more effectively while maximizing strength and rigidity.

Equipped with AX6292 Grade 12.9 Ball Joints – Every system includes a pair of Axiom Supply AX6292 Bolt-On Upper Ball Joints featuring our Grade 12.9 Extreme-Duty Ball Stud technology for exceptional strength, steering precision, and resistance to deformation under heavy loads.

Forged Torsion Leveling Keys – Heavy-duty forged keys provide up to 2" of adjustable front ride height while maintaining proper torsion-bar indexing and adjustment range.

Corrected Suspension Geometry – Addresses the unfavorable upper ball joint and control arm operating angles created when the factory torsion-bar suspension is leveled.

Increased Droop Travel – Improved upper control arm and ball joint geometry restores available downward suspension movement that can be lost when the factory suspension is raised using torsion keys alone.

Improved Alignment Capability – Increased usable caster and camber adjustment allows the truck to be properly aligned across a broader range of front suspension heights.

Dual-Position Ball Joint Mounting – Allows the ball joint to be mounted above or below the control arm mounting plate, providing additional flexibility when optimizing ball joint angle, alignment, and suspension geometry.

Premium Bushing System – High-quality bushings and precision sleeves provide smooth articulation while minimizing unwanted suspension deflection.

Service-Friendly Design – Improved grease fitting access simplifies routine ball joint maintenance and lubrication.

Built for Heavy-Duty Use – Engineered for towing, hauling, oversized tires, rough roads, job-site use, off-road environments, and everyday driving.

Lifetime Warranty Protection – Axiom suspension and steering components are backed by the Axiom No-Nonsense Lifetime Warranty for the original purchaser.

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Description

The Axiom Supply Stage 3 FOX 2.5 Performance Leveling System for 2001-2010 GM HD Trucks was developed for owners looking for more than simply raising the front of their truck.

A traditional torsion-key leveling kit can improve stance and tire clearance, but increasing front ride height also changes upper control arm position, ball joint operating angle, available droop travel, caster geometry, alignment capability, and shock operating position.

The Axiom Stage 3 System addresses the suspension as a complete system rather than simply increasing ride height.

At the foundation are Axiom Supply forged torsion leveling keys, providing up to 2" of adjustable front ride height to reduce factory rake and provide additional clearance for larger wheel and tire combinations.

But raising the truck is only the beginning.

The Stage 3 system replaces all four factory shocks with application-specific FOX 2.5 Performance Series IFP shocks.

Up front, the system utilizes the Axiom AX4074 / FOX 987-24-074, specifically sized for stock through 2.5" of front lift.

At the rear, the Axiom AX4075 / FOX 987-24-075 provides a properly matched rear shock for stock through 1" of rear lift, making it ideally suited to leveled trucks retaining near-stock rear suspension height, mild rear block configurations, and compatible airbag-assisted towing setups.

FOX's substantially larger 2.5" monotube architecture provides increased piston area, fluid capacity, and damping capability compared with conventional factory-style replacement shocks.

At the center of each shock is FOX's Internal Floating Piston system, which physically separates the shock oil from the high-pressure nitrogen gas charge. This helps prevent oil aeration and maintain predictable damping as suspension speeds and operating temperatures increase.

FOX combines this architecture with high-flow velocity-sensitive damping and vehicle-specific valving engineered around the operating characteristics of the GM HD platform.

The result is a truck that remains comfortable and composed during everyday highway driving while providing increased suspension control over broken pavement, larger bumps, washboard roads, towing loads, job sites, and off-road terrain.

The large 2.5" impact-extruded 6061-T6 aluminum shock bodies also provide excellent thermal management, transferring heat away from the shock oil to help maintain consistent damping during extended periods of demanding suspension operation.

Premium 5/8" hard chrome shock shafts, Type II clear-anodized bodies, and FOX's proven monotube construction provide the durability required for serious heavy-duty truck use.

But premium shocks cannot correct poor suspension geometry on their own.

The included Axiom Supply Heavy-Duty Upper Control Arms were engineered specifically to address the geometry changes created as front ride height increases.

Unlike many competing upper control arms designed around a predetermined amount of caster correction intended for one specific leveling height, Axiom engineered ride-height corrected caster geometry directly into the control arm design.

This gives the alignment technician usable caster adjustment throughout a broad range of front ride heights rather than forcing the truck to work around geometry intended for only one fixed lift setting.

The result is improved straight-line stability, steering return-to-center, alignment capability, suspension articulation, and overall driving characteristics whether the truck is maintained near stock height or adjusted toward the full leveling range.

The Axiom control arms also help restore available droop travel lost when the factory suspension is raised using torsion keys alone. Improved ball joint operating angles allow the suspension to move through its travel more naturally without forcing the upper ball joint toward the limits of its available articulation.

Structurally, each arm utilizes Axiom's true double-shear construction, built from matching upper and lower 3/16" laser-cut steel plates hand welded into one rigid structural assembly.

Rather than supporting the ball joint from a single mounting surface, the double-shear architecture supports the mounting area from both sides, distributing suspension loads more effectively and minimizing flex under demanding steering and suspension loads.

Each control arm is equipped with an Axiom Supply AX6292 Bolt-On Upper Ball Joint featuring our Grade 12.9 Extreme-Duty Ball Stud technology.

The serviceable bolt-in design combines exceptional strength with long-term serviceability, allowing the ball joint itself to be replaced independently without replacing the complete upper control arm.

Axiom's dual-position ball joint mounting design provides an additional level of suspension setup flexibility, allowing the ball joint to be positioned above or below the mounting plate depending on ride height and suspension configuration.

Combined with premium bushings, precision sleeves, forged leveling keys, corrected caster geometry, and four application-specific FOX 2.5 Performance Series shocks, the Stage 3 system creates a complete suspension package designed to work together from front to rear.

Whether your GM HD is a daily-driven Duramax, heavy tow rig, work truck, leveled street truck, oversized-tire build, or weekend off-road vehicle, the Axiom Supply Stage 3 FOX 2.5 Performance Leveling System delivers the ride height, caster correction, wheel travel, damping capacity, alignment capability, strength, and suspension control expected from a premium heavy-duty suspension system.

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FOX 2.5 Shock Package

Front – Axiom AX4074

FOX Part Number: 987-24-074

Position: Front

Ride Height: 0-2.5" Front Lift

Shock Body: 2.5"

Construction: Monotube IFP

Body: Impact-Extruded 6061-T6 Aluminum

Finish: Type II Clear Anodized

Shaft: 5/8" Hard Chrome

Damping: High-Flow Velocity-Sensitive

Travel: 4.39"

Extended Length: 15.69"

Compressed Length: 11.30"

Upper Mount: Stem

Lower Mount: Eyelet

Rear – Axiom AX4075

FOX Part Number: 987-24-075

Position: Rear

Ride Height: 0-1" Rear Lift

Shock Body: 2.5"

Construction: Monotube IFP

Body: Impact-Extruded 6061-T6 Aluminum

Finish: Type II Clear Anodized

Shaft: 5/8" Hard Chrome

Damping: High-Flow Velocity-Sensitive

Travel: 8.69"

Extended Length: 25.88"

Compressed Length: 17.19"

Upper Mount: Eyelet

Lower Mount: Eyelet

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Ball Joint Interchange

The included Axiom Supply AX6292 utilizes the common aftermarket bolt-in upper ball joint pattern associated with:

K6292

MOOG K6292

The AX6292 is a serviceable bolt-in ball joint designed specifically for compatible aftermarket GM HD upper control arms.

Note: K6292 interchange applies to the bolt-in ball joint used with compatible aftermarket upper control arms. It is not the same design as the factory press-in upper ball joint used in the original stamped GM control arm.

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Maintenance

Apply approximately 3 pumps of grease to each ball joint during installation.

For continued performance, service each ball joint every 5,000-7,000 miles.

Use only the amount of grease necessary to properly lubricate the joint and avoid over-greasing.

Periodically inspect ball joints, control arm bushings, torsion-key adjustment hardware, shocks, and suspension mounting hardware—particularly on vehicles used for heavy towing, off-road driving, or equipped with oversized tires.

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Includes

(2) Axiom Supply Heavy-Duty Upper Control Arms

(2) Axiom Supply AX6292 Grade 12.9 Bolt-On Upper Ball Joints

(2) Axiom Supply Forged Torsion Leveling Keys

(2) Axiom Supply AX4074 FOX 2.5 Performance Series Front Shocks

• FOX 987-24-074

(2) Axiom Supply AX4075 FOX 2.5 Performance Series Rear Shocks

• FOX 987-24-075

(4) Control Arm Sleeves

(8) Control Arm Bushings

(1) Complete Installation Hardware Kit

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Interchange

2001-2010 Chevy Silverado 2500HD FOX 2.5 Leveling Kit, 2001-2010 GMC Sierra 2500HD FOX 2.5 Leveling Kit, Silverado 3500 FOX Leveling Kit, Silverado 3500HD FOX Leveling Kit, Sierra 3500 FOX Leveling Kit, Sierra 3500HD FOX Leveling Kit, GM HD FOX 2.5 Leveling System, Duramax FOX 2.5 Leveling Kit, LB7 FOX Leveling Kit, LLY FOX Leveling Kit, LBZ FOX Leveling Kit, LMM FOX Leveling Kit, GM HD Upper Control Arms, GM HD Caster Corrected Upper Control Arms, GM HD Forged Torsion Keys, FOX 987-24-074, FOX 98724074, FOX 987-24-075, FOX 98724075, Axiom AX4074, Axiom AX4075, K6292 Upper Ball Joint, AX6292 Upper Ball Joint

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The Axiom No-Nonsense Lifetime Warranty

Our suspension components are warrantied for life to the original purchaser against manufacturer defects, premature wear, or breakage.

Push it to the limit—we don't care.

If the part lets you down, we'll make it right.