FOX 987-24-033 Perf 2.5 IFP HTO Front Shock 20-25 Silverado/Sierra HD 4-6in Lift

Vehicle Fitment

• 2020-2025 Chevrolet Silverado 2500 HD (4WD; all cab configurations - Regular Cab, Double Cab, Crew Cab; all bed lengths; gas and diesel) - Confirmed fitment; front shock
• 2020-2025 Chevrolet Silverado 3500 HD (4WD; all cab configurations; all bed lengths; gas and diesel) - Confirmed fitment; front shock
• 2020-2025 GMC Sierra 2500 HD (4WD; all cab configurations; all bed lengths; gas and diesel) - Confirmed fitment; front shock
• 2020-2025 GMC Sierra 3500 HD (4WD; all cab configurations; all bed lengths; gas and diesel) - Confirmed fitment; front shock
• Designed for vehicles with 4-6" of front lift. Confirm your specific front lift height falls within this range before ordering. FOX offers companion 987-series front variants for the 2020+ platform at other lift ranges: 987-24-008 (0-1"), 987-24-010 (1.5-2.5"), and 987-24-024 (6.5"). For the equivalent front shock on the prior 2011-2019 generation at the same lift range, see 987-24-032.
• 4WD models only.
• 2020+ generation (T1XX platform) only. The 2011-2019 third-generation Silverado/Sierra HD uses different front suspension geometry and mounting - it is not covered by this part number.

Application Notes

• The 987-24-033 covers the T1XX fourth-generation GM heavy-duty platform (2020-2025 Silverado/Sierra 2500/3500 HD) at 4-6" of front lift - a significant lift height that substantially alters the front suspension geometry of these trucks. At 4-6", changes to caster angle, ball joint load angles, differential drop requirements, and IFS geometry are meaningful, making lift-range-specific valving more important, not less, than at moderate lift heights. The 987-24-033 is calibrated for the spring rates, motion ratios, and suspension behavior of the 2020+ GM HD front end at this specific elevation.
• At 4-6" of front lift, complementary hardware is typically required beyond shock replacement alone - aftermarket upper control arms (UCAs) to restore ball joint angles, differential drop or relocation brackets, extended brake lines, and alignment correction. Verify that all complementary suspension components appropriate to your specific lift system are in place before installation.
• HTO (Hydraulic Top Out) is especially relevant at 4-6" of lift on the GM HD front suspension. At this elevation, the front suspension's increased droop travel and heavier unsprung weight from the large-diameter, high-load-range tires common on 4-6" lifted work and off-road builds create more frequent and more forceful top-out events during off-road use and even over aggressive road irregularities. HTO's progressive hydraulic resistance at the end of extension travel converts these from abrupt mechanical impacts into controlled decelerations, protecting ball joints, tie rod ends, and UCAs from repeated shock loading.
• The 2020+ Silverado/Sierra 2500/3500 HD carries the same payload and towing demands as its predecessor - the 987-24-033's valving accounts for the front axle weight and spring rates under both loaded and unloaded conditions on the T1XX platform.
• Companion rear shock for the same platform and lift range: 987-24-035 (2011-2025 Silverado/Sierra 2500/3500 HD rear, 4-6" lift).
• Sold individually - one shock per order. Two are required for a complete front axle replacement.
• Installation is a bolt-on direct replacement for the factory front shock - no modification to shock mounting points is required for the shock itself.

Features

• 2.5" body diameter - the 987-series 2.5" body provides substantially more oil volume than a 2.0" body shock, supporting greater heat capacity for sustained use and a larger piston for more precise damping force curves. At 4-6" of lift, where the front suspension is working harder against altered geometry and increased unsprung weight from large aftermarket tires, the 2.5" body's thermal advantage over a 2.0" body becomes meaningful during extended off-road use or high-speed corrugated driving.
• 6061-T6 aluminum body, Type II anodized - efficient heat dissipation and corrosion resistance in the demanding underbody environment of a heavy-duty truck operating in varied weather, terrain, and road conditions.
• Internal Floating Piston (IFP) - physically separates shock oil from the high-pressure nitrogen gas charge to prevent aeration under aggressive or sustained cycling. The smooth body (no external reservoir) configuration keeps the package compact for the space constraints of the 2020+ GM HD front suspension while providing IFP-level consistency over repeated cycling.
• Hydraulic Top Out (HTO) - at the end of the shock's extension travel, the HTO piston routes oil through a secondary shim stack that provides progressive hydraulic resistance, decelerating the shaft before it contacts mechanical travel limits. At 4-6" of lift with the increased droop travel and heavier unsprung weight that characterize this build profile, HTO meaningfully reduces the harshness and stress of top-out events transmitted through the front suspension to steering components and chassis mounting points.
• Vehicle and lift-specific valving - calibrated for the T1XX platform's 2020+ front suspension geometry, spring rates, and axle weight at 4-6" of lift. Not adapted from a lesser-lift tune or a generic heavy-duty base valving curve.
• 5/8" hard chrome shaft - provides bending resistance under the lateral loads generated by the significantly altered geometry of a 4-6" lifted HD IFS front end, with hard chrome surface treatment for long-term seal interface durability.
• Bolt-on direct fit - installs to the factory front shock mounting hardware on the 2020-2025 Silverado/Sierra 2500/3500 HD without modification to mounting points.

Specifications

• Part Number: 987-24-033
• Series: FOX Performance Series 2.5
• Type: Smooth Body IFP HTO Shock
• Position: Front
• Vehicle Fitment: 2020-2025 Chevrolet Silverado 2500/3500 HD; 2020-2025 GMC Sierra 2500/3500 HD (4WD)
• Lift Range: 4-6"
• Body Diameter: 2.5"
• Body Material: 6061-T6 aluminum, Type II anodized
• Shaft: 5/8" hard chrome
• Reservoir Type: Internal Floating Piston (IFP) - smooth body, no external reservoir
• HTO (Hydraulic Top Out): Yes
• Valving: Vehicle/lift-specific; position-sensitive
• Installation: Bolt-on direct fit
• Quantity: 1 shock per order
• Warranty: 1-year limited warranty

Included Components

• 1x FOX 987-24-033 Performance Series 2.5 Smooth Body IFP HTO Front Shock

Product Description

The FOX 987-24-033 is the Performance Series 2.5 Smooth Body IFP HTO front shock for the 2020-2025 Chevrolet Silverado 2500/3500 HD and GMC Sierra 2500/3500 HD 4WD at 4-6" of front lift - the high-lift front shock for the fourth-generation T1XX GM heavy-duty platform. At 4-6", the front IFS geometry of the Silverado/Sierra HD departs substantially from stock specification, making a shock specifically valved for this elevation essential rather than optional. The 987-24-033 is calibrated for the T1XX platform's front spring rates, motion ratios, and axle weight at this lift height, accounting for the loaded and unloaded operating conditions that characterize real-world 2500/3500 HD use.

The 2.5" body provides the oil volume and piston diameter necessary to manage the increased thermal loads and damping force demands of a heavily lifted HD front suspension - where large-diameter tires, increased unsprung weight, and altered geometry make the front shock work harder than at stock height. The IFP maintains consistent oil/gas separation across repeated aggressive cycling without the external reservoir's packaging footprint, keeping installation compact within the T1XX's front suspension space constraints. HTO's secondary shim stack decelerates shaft extension at travel limits, reducing the intensity of the more frequent and forceful top-out events that 4-6" of lift and heavier tires create in the GM HD front suspension during off-road use.

At 4-6" of front lift, the 987-24-033 is one component of a complete suspension system - aftermarket UCAs, differential drop hardware, extended brake lines, and alignment correction are typically required alongside it. The companion rear shock for the same platform and lift range is the 987-24-035. The 987-24-033 is sold as a single shock; two are required for a complete front replacement. FOX backs it with a 1-year limited warranty.