Fox 2.5 Performance Series IFP HTO Rear Shock | Single | 0-1" Lift | 2011-2025 Chevy Silverado/GMC Sierra 2500HD/3500HD | SKU 987-24-009
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Shipping & Delivery
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Fitment, Shipping & Product Support
The Fox 2.5 Performance Series IFP HTO Rear Shock (SKU 987-24-009) is a step-up heavy-duty rear shock for the 2011–2025 Chevrolet Silverado and GMC Sierra 2500HD/3500HD, running stock height to 1" of rear lift. The larger 2.5" Type II anodized aluminum body increases oil volume for superior heat dissipation and corrosion resistance versus the standard 2.0" Fox shock. Internal Floating Piston (IFP) separates shock oil from high-pressure nitrogen for optimized, consistent damping. Hydraulic Top Out (HTO) technology uses a secondary shim stack to provide position-sensitive rebound damping control, reducing harsh top-outs — particularly beneficial after installing heavier, more aggressive tires or on applications lifted higher than OEM spec. Vehicle-specific valving and larger pistons. Bolt-on installation with included hardware — no modifications needed. Sold as a single rear shock.
Component Specifications
| Spec | Detail |
|---|---|
| SKU / Part Number | 987-24-009 |
| Brand | Fox |
| Series | 2.5 Performance Series |
| Position | Rear |
| Quantity | Single shock — order 2 for a complete rear pair |
| Body | 2.5" Type II anodized aluminum |
| Damping | IFP (Internal Floating Piston) + HTO (Hydraulic Top Out) |
| HTO Function | Secondary shim stack provides position-sensitive rebound damping, reduces harsh top-outs |
| Lift Range | 0–1" rear lift |
| Application | Towing, hauling, heavier/aggressive tire setups, sustained heavy-duty use |
| Installation | Bolt-on — included hardware, no modifications needed |
| Sold As | Each |
What Is and Is NOT Included
| Item | Included |
|---|---|
| 1x rear shock | ✓ |
| Mounting hardware | ✓ |
| Second rear shock | ✗ NOT included — order quantity 2 for a pair |
| Front shocks | ✗ NOT included — sold separately under a different part number (e.g., 987-24-008) |
Fox 2.5 HTO vs. Fox 2.0 — Choose Your Tier
| Spec | Fox 2.0 (980-24-664) | Fox 2.5 HTO (987-24-009, this listing) |
|---|---|---|
| Body diameter | 2.0" | 2.5" — greater oil volume, more heat capacity |
| Top-out control | Standard IFP | IFP + HTO — position-sensitive rebound damping |
| Confirmed lift range | 0-2.5" (per Fox's own fitment data) | 0-1" |
| Confirmed years | 1999-2019 | 2011-2025 |
| Best for | Standard duty, daily driving, moderate towing | Heavier/aggressive tires, lifted applications, sustained heavy-duty use |
Verified Fitment
| Vehicle | Years | Lift Range | Status |
|---|---|---|---|
| Chevrolet Silverado 2500HD | 2011–2025 | 0–1" | ✓ |
| Chevrolet Silverado 3500HD | 2011–2025 | 0–1" | ✓ |
| GMC Sierra 2500HD | 2011–2025 | 0–1" | ✓ |
| GMC Sierra 3500HD | 2011–2025 | 0–1" | ✓ |
| Silverado/Sierra 1500 | Any | Any | ✗ Different rear suspension geometry |
| Silverado/Sierra 2500HD/3500HD | 2010 and earlier | Any | ✗ Different chassis generation — different Fox part number required |
Critical Compatibility
| Configuration | Notes |
|---|---|
| 2010 and earlier Silverado/Sierra HD | Does not fit — different chassis generation |
| Rear lift exceeding 1" | Requires a different Fox 2.5 HTO part number (e.g., 987-24-011 for 1.5-2.5" lift, 987-24-035 for 4-6" lift) |
| 3500HD DRW (Dually) | Confirm rear shock mounting geometry matches SRW spec before ordering |
| Long-travel or coilover conversion suspension | Not compatible |
| Mismatched left/right shocks | Replace in pairs for handling balance |
Common Questions
What does HTO actually do?
HTO stands for Hydraulic Top Out. A secondary shim stack inside the shock provides position-sensitive rebound damping control, slowing the shock shaft as it nears full extension. This reduces the harsh "clunk" or jarring feeling of a shock topping out — especially noticeable after installing heavier tires or on a truck lifted above OEM height.
What's the real difference between this and the standard Fox 2.0?
The larger 2.5" body holds more oil and nitrogen, improving heat dissipation under sustained heavy use. The HTO technology adds the position-sensitive top-out control that the standard 2.0 IFP shock doesn't have. This is the step-up choice for trucks that tow or haul frequently, or run heavier/more aggressive tire setups.
Does this fit my 2009 Silverado 2500HD?
No. Confirmed fitment for this exact part number starts at 2011. A 2009 truck needs a different Fox part number for the earlier chassis generation.
Do I need one or two?
This listing is for a single shock. Order quantity 2 for a complete rear pair, and replace both sides together for balanced handling.
The Obsidian Take
The 987-24-009 is for the 2011–2025 Silverado/Sierra 2500HD/3500HD owner who tows or hauls frequently, or who's running heavier/more aggressive tires, and wants the larger 2.5" body and Hydraulic Top Out control over the standard Fox 2.0 shock. More oil volume, better heat dissipation, smoother top-out behavior.
If your truck is stock-to-light-duty without aggressive tires, the standard Fox 2.0 (980-24-664) likely covers your needs at a lower cost. This HTO upgrade earns its price when the truck is actually working — sustained towing, max payload, or oversized tire setups that make harsh top-outs a real, repeated annoyance.
Non-Returnable Notice: Once installed, this unit is non-returnable. Confirm model year, lift height, and SRW/DRW configuration before ordering.
⚠️ California Proposition 65 Warning: This product may expose you to chemicals known to the State of California to cause cancer or reproductive harm. For more information visit P65Warnings.ca.gov.
Specifications sourced from Fox and authorized distributor documentation. Obsidian Forged Auto Supply is an authorized Fox dealer. Manufacturer specifications are subject to change without notice.