FOX 987-24-031 Perf 2.5 IFP HTO Front Shock 2011-19 Silverado/Sierra HD 1.5-3.5"

Vehicle Fitment

• 2011-2019 Chevrolet Silverado 2500 HD (4WD; all cab configurations - Regular Cab, Double Cab, Crew Cab; all bed lengths; gas and diesel) - Confirmed fitment; front shock
• 2011-2019 Chevrolet Silverado 3500 HD (4WD; all cab configurations; all bed lengths; gas and diesel) - Confirmed fitment; front shock
• 2011-2019 GMC Sierra 2500 HD (4WD; all cab configurations; all bed lengths; gas and diesel) - Confirmed fitment; front shock
• 2011-2019 GMC Sierra 3500 HD (4WD; all cab configurations; all bed lengths; gas and diesel) - Confirmed fitment; front shock
• Designed for vehicles with 1.5-3.5" of front lift. Confirm your specific front lift height is within this range before ordering. FOX offers companion 987-series front variants for other lift ranges on this platform and generation - the 987-24-032 covers 4-6" front lift for the same 2011-2019 generation. For 2020+ Silverado/Sierra 2500/3500 HD at similar lift ranges, see the 987-24-010 (1.5-2.5") and 987-24-033 (4-6").
• 4WD models only.
• 2011-2019 generation only (K2XX platform for the 2500/3500 HD). The 2020+ fourth-generation Silverado/Sierra HD uses different front suspension geometry and mounting - it is not covered by this part number.

Application Notes

• The 987-24-031 covers the K2XX-generation GM heavy-duty platform (2011-2019 Silverado/Sierra 2500/3500 HD) at 1.5-3.5" of front lift. This generation uses a solid front axle with coil springs (2WD) or an independent front suspension with torsion bars (2500 HD) or coil springs (3500 HD) - the 987-24-031 is valved specifically for the front suspension geometry, spring rates, and weight distribution of this generation at 1.5-3.5" of elevation above stock.
• HTO (Hydraulic Top Out) is particularly relevant at 1.5-3.5" of lift on the GM HD front suspension. Lifted front suspension - particularly with heavier, larger aftermarket tires common on work-use 2500/3500 HD builds - increases the unsprung weight and travel distance that the front shock must manage, making top-out events at full droop more frequent and more forceful than on a stock-height truck. HTO's secondary shim stack absorbs and decelerates these events hydraulically, protecting steering components and providing a more controlled feel under trail and off-road use.
• The 2011-2019 Silverado/Sierra 2500/3500 HD platform carries significant factory payload and towing capacity, and the shock valving of the 987-24-031 accounts for the front axle weight and spring rates common to both loaded and unloaded states on this platform.
• Installation is a direct bolt-on replacement for the factory front shock - no modification to shock mounting hardware is required for the shock itself. At 1.5-3.5" of lift, alignment correction and potentially extended front brake lines may be required depending on the specific lift system installed.
• This is a single shock - one unit per order. Two are required for a complete front axle replacement.

Features

• 2.5" body diameter - the 987-series 2.5" body provides substantially more oil volume than the 985-series 2.0" body, supporting greater heat capacity for sustained use and a larger piston for more precise damping force control. On a heavy-duty truck platform that regularly carries payload and tows, sustained shock cycling under load generates heat more quickly than a light-duty application - the 2.5" body's increased oil volume raises the heat capacity ceiling before fade onset.
• 6061-T6 aluminum body, Type II anodized - efficient heat dissipation, corrosion resistance, and durable surface protection for the underbody environment of a heavy work truck operating in varying weather and road conditions.
• Internal Floating Piston (IFP) - separates shock oil from the high-pressure nitrogen gas charge to prevent aeration under sustained or aggressive cycling. The smooth body configuration with IFP (no external reservoir) is compact and practical for the front suspension mounting constraints of the 2011-2019 GM HD platform.
• Hydraulic Top Out (HTO) - at the end of extension travel, the HTO piston routes oil through a secondary shim stack to decelerate the shaft progressively before it reaches mechanical limits. At 1.5-3.5" of lift, increased front droop travel and heavier unsprung weight from oversized tires amplify top-out events - HTO converts these from abrupt impacts into controlled decelerations, reducing steering kickback and protecting ball joints and tie rod ends from repeated shock loading.
• Vehicle and lift-specific valving - the 987-24-031 is calibrated specifically for the 2011-2019 Silverado/Sierra 2500/3500 HD front suspension geometry, spring rates, and axle weight at 1.5-3.5" of lift. The valving accounts for both loaded (payload/towing) and unloaded conditions on this platform.
• 5/8" hard chrome shaft - resists bending under the lateral loads generated by the altered geometry of a lifted HD front suspension, with hard chrome surface treatment for long-term seal interface wear resistance.
• Bolt-on direct fit - installs to the factory front shock mounting hardware without modification to mounting points.

Specifications

• Part Number: 987-24-031
• Series: FOX Performance Series 2.5
• Type: Smooth Body IFP HTO Shock
• Position: Front
• Vehicle Fitment: 2011-2019 Chevrolet Silverado 2500/3500 HD; 2011-2019 GMC Sierra 2500/3500 HD (4WD)
• Lift Range: 1.5-3.5"
• 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 987-24-031 Performance Series 2.5 Smooth Body IFP HTO Front Shock

Product Description

The FOX 987-24-031 is the Performance Series 2.5 Smooth Body IFP HTO front shock for the 2011-2019 Chevrolet Silverado 2500/3500 HD and GMC Sierra 2500/3500 HD 4WD at 1.5-3.5" of front lift. It is the mid-lift-range front shock for the K2XX-generation GM heavy-duty platform, positioned between the stock-height 987-24-030 and the 4-6" lift 987-24-032 within the 987-series front shock lineup for this generation. The 2020+ generation Silverado/Sierra HD uses a different platform and is not covered by this part number.

The 2.5" body is the key upgrade over the 985-series 2.0" body for this application - more oil volume means a higher thermal ceiling before fade, and a larger piston supports more precise damping force curves across the velocity spectrum of inputs that a 1.5-3.5" lifted HD truck generates during towing, payload hauling, and off-road use. The IFP smooth body maintains consistent oil/gas separation without the external reservoir's packaging footprint, keeping the installation clean within the GM HD front suspension's space constraints. The HTO secondary shim stack progressively decelerates shaft extension at travel limits, which at 1.5-3.5" of lift reduces the intensity of droop top-out events that heavier aftermarket tires and increased suspension travel amplify over stock.

Valving is calibrated for the 2011-2019 GM HD platform's front spring rates, geometry, and weight at this specific lift range - accounting for the loaded and unloaded conditions that define real-world 2500/3500 HD use. Installation is a direct bolt-on at the factory front shock mounting points. The 987-24-031 is sold as a single shock; two are required for a complete front replacement. FOX backs it with a 1-year limited warranty.