Vehicle Fitment

• 2003–2024 Toyota 4Runner (SR5, SR5 Premium, TRD Off-Road, TRD Off-Road Premium, TRD Pro, Trail, Limited, 40th Anniversary Edition, Venture, 4WD and RWD)
• 2003–2009 Lexus GX470 (Base, 4WD)
• 2010–2023 Lexus GX460 (Base, Premium, Luxury, Black Line Edition, 4WD)

Fitment Notes

• Does NOT fit any Toyota 4Runner or Lexus GX equipped with the X-REAS (Cross-linked Electronically Actuated Suspension) system — X-REAS equipped vehicles require complete hydraulic system replacement
• Rear position only — Left (Driver) side
• Designed for vehicles at stock ride height or with up to 2.5 inches of rear suspension lift installed
• Fits both 4WD and RWD (2WD) configurations on the Toyota 4Runner
• Sold individually — for a complete rear upgrade, pair with Bilstein 25-326376 (Rear Right / Passenger Side)
• Installation may require drilling, cutting, or welding depending on application and mounting location
• Optional billet aluminum reservoir clamp available separately for a cleaner installation appearance

Features

• Bilstein B8 8100 Bypass Series — motorsports-inspired, position-sensitive, externally adjustable bypass shock absorber engineered as a direct-fit upgrade for lifted trucks and SUVs
• Dual tube externally adjustable bypass design with independent "Incremental Flow" adjusters for both compression and rebound — allowing precise, finite damping tuning without removal
• Position-sensitive damping delivers different compression and rebound characteristics depending on shaft position in the stroke, providing improved small-bump compliance and rock-solid bottom-out control
• 60mm large bore hard anodized aluminum piston provides a greater range of damping control and exceptional long-term durability under repeated off-road stress
• Bottom hose and remote reservoir exit port design delivers increased compression control throughout the full shock cycle
• Remote reservoir dramatically increases oil volume and heat dissipation capacity, preventing fade and maintaining consistent damping during extended high-intensity off-road use
• Bolt-on aluminum anodized chassis reservoir mount included for straightforward, secure reservoir installation
• EVO Grey finish is corrosion-resistant and delivers a premium, purpose-built aesthetic
• Maximizes wheel travel for enhanced off-road articulation while retaining composure and comfort on paved surfaces
• Factory shock mounting bolts are reused — all necessary washers, bushings, and hardware included

Specifications

• Part Number: 25-326369
• Series: B8 8100 Bypass
• Position: Rear — Left (Driver Side)
• Body Diameter: 60mm
• Body Design: Bypass (Non-Coilover)
• Internal Design: Monotube
• Extended Length: 14.72 in
• Collapsed Length: 24.09 in
• Upper Mount Type: Stem
• Lower Mount Type: Eye (19.2mm)
• Adjustable Damping: Dual — Independent Compression and Rebound (Click Adjuster Knobs)
• Reservoir: External Remote Reservoir (included)
• Reservoir Mount: Bolt-On Aluminum Anodized Chassis Mount (included)
• Finish: EVO Grey
• Lift Range: 0–2.5 inches (rear)
• Spring Seat: Not Included
• Quantity: 1 shock absorber per package

Included Components

• 1x Bilstein B8 8100 Bypass Rear Left Shock Absorber (25-326369)
• 1x Bolt-On Aluminum Anodized Remote Reservoir Chassis Mount
• 1x Hardware Kit (washers, bushings, and nuts)
• 1x Installation Instructions

Product Description

The Bilstein 25-326369 B8 8100 Bypass Rear Left Shock Absorber is the most advanced direct-fit shock absorber Bilstein offers for the 2003–2024 Toyota 4Runner, 2003–2009 Lexus GX470, and 2010–2023 Lexus GX460. Designed for serious off-road enthusiasts who demand race-level tunability without sacrificing street manners, the B8 8100 Bypass series brings externally adjustable, position-sensitive damping technology to your truck in a bolt-on package. Whether your vehicle sits at stock height or has up to 2.5 inches of rear lift installed, this shock is engineered to deliver controlled, predictable performance across the full range of driving conditions. It is compatible with both 4WD and RWD Toyota 4Runner variants, but does not fit any vehicle equipped with the factory X-REAS interconnected suspension system.

At the heart of the 25-326369 is Bilstein's dual tube externally adjustable bypass design, featuring independent compression and rebound "Incremental Flow" click adjusters that allow you to dial in your exact damping preference without removing the shock from the vehicle. The 60mm large bore hard anodized aluminum piston gives this shock an exceptional range of damping capability and industry-leading durability under repeated heavy impacts. The position-sensitive bypass design means the shock responds differently based on where it is in its stroke — offering soft, compliant behavior for small trail chop and transitioning to firm, controlled resistance near the limits of travel to prevent harsh bottom-out. The external remote reservoir, connected via a bottom hose, dramatically increases oil volume and thermal capacity, keeping performance consistent during the most demanding off-road runs.

Installation is straightforward for an experienced builder, though some applications may require drilling, cutting, or welding for reservoir bracket mounting. The included bolt-on aluminum anodized reservoir chassis mount and hardware kit cover everything needed to complete the installation, and the factory shock mounting bolts are reused to keep things clean. This shock is sold individually as the left (driver) side unit — to complete a full rear upgrade, it must be paired with Bilstein part number 25-326376, the matching right (passenger) side shock. For Toyota 4Runner and Lexus GX owners who demand the highest level of off-road shock performance available in a direct-fit application, the Bilstein B8 8100 Bypass represents the pinnacle of what the B8 lineup has to offer.