KYB 555056 Shock Absorber - Rear

KYB Gas-a-just Rear Shock for Super Duty

The KYB Gas-a-just 555056 is a rear suspension shock absorber built for Ford Super Duty trucks that need firmer control under load. It uses a monotube design with separate gas and oil chambers for quick response, consistent damping, and reduced fade during demanding driving.

Key Features

• Monotube shock design with air-free hydraulic response and high-pressure nitrogen gas support
• Up to 25% more damping performance than original equipment shocks
• Engineered for Ford Super Duty rear applications, including work, towing, and larger tire and wheel setups
• Triple chrome plated piston rod helps reduce seal wear and fluid leakage
• Improves steering response and helps maintain suspension performance for electronic safety systems
• Dust cover included

Product Details

Gas-a-just is KYB’s performance-oriented shock line for drivers who want more control than a conventional twin-tube design. The 555056 uses a high-pressure monotube layout that separates gas and oil, which supports fade-free operation and immediate damping response. For rear suspension service on Ford F-250 Super Duty and Ford F-350 Super Duty trucks, this shock is a direct-fit option for applications that see heavy use, towing, or added unsprung weight from larger wheels and tires. This part number is 555056, and it cross-references Monroe Shocks & Struts 911267 for the same application.

Common Problems This Shock Can Address

• Excessive rear bounce after bumps or dips
• Reduced control when towing or carrying heavy loads
• Shock fade during repeated suspension movement
• Loose or delayed steering response from worn rear damping
• Oil leakage from worn shock seals

Installation Notes and Fitment

Fits 2011-2016 Ford F-250 Super Duty, rear, with Off Road Suspension; Gas-a-just. Fits 2005-2016 Ford F-250 Super Duty, rear, install a monotube shock absorber to enhance performance; Gas-a-just. Fits 2008-2016 Ford F-350 Super Duty, rear, without Off Road Suspension; Gas-a-just. Verify compressed length 17.87 in., extended length 29.29 in., stroke length 11.42 in., lower mount E2(12X38), and upper mount E1 before installation. The KYB Gas-a-just 555056 is a rear shock for Ford F-250 Super Duty and Ford F-350 Super Duty applications, so confirm the vehicle’s suspension configuration matches the listed notes.

Quality Assurance

KYB designs Gas-a-just shocks with a monotube construction that separates gas and oil for consistent damping and reduced fade. The triple chrome plated piston rod is used to help limit seal wear and support long-term sealing performance.