Fox 2.5 HTO Performance Front Shock | Single | 0-2.5 in Lift | 2011-2026 GM 2500HD/3500HD

Fox 2.5 HTO Performance Series Front Shock | Single Unit | 0–2.5" Front Lift | 2011–2026 Chevy Silverado / GMC Sierra 2500HD & 3500HD

The Fox 2.5 HTO Performance Series front shock (SKU: AX4010) is a step-up heavy-duty front shock engineered for 2011–2026 Chevrolet Silverado 2500HD/3500HD and GMC Sierra 2500HD/3500HD trucks running stock height or up to 2.5" of front lift. The larger 2.5" aluminum body increases oil volume for superior heat capacity and fade resistance vs. the Fox 2.0 AX189 (0–3" front lift). HTO (High Travel Output) valving delivers controlled, consistent damping under sustained towing, hauling, and rough-road conditions. The IFP (Internal Floating Piston) design separates oil and nitrogen gas to maintain consistent damping through heat cycles. Tuned specifically for the GM HD front IFS chassis — not a universal shock. Sold as a single front shock.

Verified Fitment (OFAS Standard)

• Chevy Silverado 2500HD (Front): 2011–2026 — stock height to 2.5" front lift
• Chevy Silverado 3500HD (Front): 2011–2026 — stock height to 2.5" front lift
• GMC Sierra 2500HD (Front): 2011–2026 — stock height to 2.5" front lift
• GMC Sierra 3500HD (Front): 2011–2026 — stock height to 2.5" front lift

Does NOT fit: 2010 or earlier Silverado/Sierra HD (different front suspension geometry — use AX663 for 2001–2010). Does not fit Silverado/Sierra 1500. Does not fit trucks with more than 2.5" of front lift — a longer-travel shock is required (note: Fox 2.0 AX189 covers up to 3" if needed). Not compatible with long-travel or coilover conversion systems.

Fox 2.5 HTO vs. Fox 2.0 AX189 (Same Platform)

• Body diameter: 2.5" (vs. 2.0" on AX189) — greater oil volume, superior heat capacity
• Valving: HTO (High Travel Output) — tuned for sustained heavy-load damping vs. standard IFP valving on AX189
• Lift range: 0–2.5" (vs. 0–3" on AX189) — if running 2.5–3" of front lift, use AX189 instead
• Price: $346.95 (vs. $229.95 for AX189) — recommended for high-frequency towing, max payload, or extreme duty cycles
• Weight: 8 lbs (vs. 7 lbs for AX189)

Technical Specifications

• SKU: AX4010
• Series: Fox 2.5 HTO Performance Series
• Position: Front
• Quantity: Single shock (order 2 for a complete front pair)
• Body: 2.5" aluminum — increased oil volume vs. 2.0" Fox 2.0
• Damping: HTO valving + IFP (Internal Floating Piston)
• Lift Range: 0–2.5" front lift
• Weight: 8 lbs
• Application: High-frequency towing, max payload, sustained heavy-duty use

Installation Notes

• Sold as single: This listing is for one (1) front shock. Order quantity 2 for a complete front replacement pair.
• Lift confirmation required: Verify front lift height is 0–2.5" before ordering. If running 2.5–3" of front lift, use Fox 2.0 AX189 instead — this shock does not cover the full 3" range.
• Generation confirmation: This shock fits 2011–2026 GM HD only. For 2001–2010 applications, use AX663 (Fox 2.0) instead.
• Torque specs: Upper and lower mounting hardware — torque to OEM specification for GM 2500HD/3500HD front shock mounts (verify in Fox install sheet or GM service manual).
• Alignment recommended: A front-end alignment check is recommended after front shock replacement, particularly if the truck has been running worn shocks.
• Replacement interval: Inspect for oil weeping, fade, or excessive body heat after installation. Fox 2.5 shocks are rebuildable — retain the shock body for future service.
• Pairing note: For optimal handling balance, replace front shocks in pairs. Mismatched damping rates between left and right will cause instability under braking and cornering.

Installation Warning

Do not install on 2010 or earlier GM HD trucks — front suspension geometry is incompatible. Do not install on trucks with more than 2.5" of front lift — use AX189 for lifts up to 3". Sold as a single unit — verify quantity before ordering. Once installed, the unit is non-returnable.

What is your current front lift height (confirm 0–2.5"), tow/payload frequency, and are you replacing one shock or a complete front pair — confirm whether the 2.5 HTO or Fox 2.0 AX189 is the right spec for your lift height and duty cycle?