Fox 2.5 HTO Performance Rear Shock | Single | 0-1 in Lift | 1999-2026 Ford F-250/F-350

Fox 2.5 HTO Performance Series Rear Shock | Single Unit | 0–1" Rear Lift | 1999–2026 Ford F-250 / F-350 Super Duty

The Fox 2.5 HTO Performance Series rear shock (SKU: AX4001) is a step-up heavy-duty rear shock engineered for 1999–2026 Ford F-250 and F-350 Super Duty trucks running stock height or up to 1" of rear lift. The larger 2.5" aluminum body increases oil volume for superior heat capacity and fade resistance vs. the Fox 2.0 (AX151). 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 F-250 and F-350 chassis — not a universal shock. Sold as a single rear shock.

Verified Fitment (OFAS Standard)

• Ford F-250 Super Duty (Rear): 1999–2026 — stock height to 1" rear lift
• Ford F-350 Super Duty (Rear): 1999–2026 — stock height to 1" rear lift

Does NOT fit: Ford F-450 or F-550 (different rear suspension geometry). Does not fit trucks with more than 1" of rear lift — a longer-travel shock is required. Not compatible with long-travel or coilover conversion suspension systems. Does not fit F-150.

Fox 2.5 HTO vs. Fox 2.0 (AX151)

• Body diameter: 2.5" (vs. 2.0" on AX151) — greater oil volume, superior heat capacity
• Valving: HTO (High Travel Output) — tuned for sustained heavy-load damping vs. standard IFP valving on AX151
• Price: $346.95 (vs. $229.95 for AX151) — recommended for high-frequency towing, max payload, or extreme duty cycles
• Weight: 8 lbs (vs. 7 lbs for AX151)

Technical Specifications

• SKU: AX4001
• Series: Fox 2.5 HTO Performance Series
• Position: Rear
• Quantity: Single shock (order 2 for a complete rear pair)
• Body: 2.5" aluminum — increased oil volume vs. 2.0" Fox 2.0
• Damping: HTO valving + IFP (Internal Floating Piston)
• Lift Range: 0–1" rear 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) rear shock. Order quantity 2 for a complete rear replacement pair.
• Lift confirmation required: Verify rear lift height is 0–1" before ordering. Installing on a truck with more than 1" of rear lift will result in incorrect shock travel and potential bottoming or topping out.
• Torque specs: Upper and lower mounting hardware — torque to OEM specification for Ford F-250/F-350 rear shock mounts (verify in Fox install sheet or Ford service manual). Do not overtorque aluminum-bodied shock mounts.
• 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 rear shocks in pairs. Mismatched damping rates between left and right will cause instability under load.

Installation Warning

Do not install on trucks with more than 1" of rear lift — incorrect shock travel will result in bottoming or topping out under load. This shock is not compatible with long-travel or coilover conversion systems. Sold as a single unit — verify quantity before ordering. Once installed, the unit is non-returnable.

What is your current rear lift height, tow/payload frequency, and are you replacing one shock or a complete rear pair — confirm whether the 2.5 HTO or Fox 2.0 (AX151) is the right spec for your duty cycle?