KYB 554389 Shock Absorber - Rear

KYB Gas-a-Just Rear Shock for Silverado and Sierra HD

The KYB Gas-a-Just 554389 is a monotube rear shock absorber built for heavy-duty GM trucks that need firmer control without sacrificing everyday ride quality. It is engineered for Chevrolet Silverado 2500 HD, Silverado 3500 HD, GMC Sierra 2500 HD, and Sierra 3500 HD rear applications across multiple model years.

Gas-a-Just shocks use separate gas and oil chambers for quick response and consistent damping. This design helps maintain control under load, during towing, and on trucks running larger wheels and tires.

Key Features

• Monotube shock design for responsive damping and stable performance
• Up to 25% more damping performance than original equipment shocks
• High-pressure nitrogen gas separates from the oil to reduce fade from aeration
• Triple chrome plated piston rod helps reduce seal wear and fluid leakage
• Higher gas pressure improves steering response and suspension control
• Components and valving are tuned for GM truck applications
• Dust cover included

Product Details

KYB Gas-a-Just 554389 is designed for rear suspension use on GM heavy-duty pickups where added control is needed for work duty, towing, or upgraded tire and wheel packages. The monotube construction keeps the hydraulic and gas areas separate, which supports consistent damping and immediate response when road conditions change. For Chevrolet Silverado HD and GMC Sierra HD owners, this shock provides a direct-fit suspension upgrade focused on control, stability, and predictable handling.

This part cross-references Monroe Shocks & Struts 911303 for the same application.

What It Helps 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 on heavy-duty trucks
• Wear related to fluid leakage from aging shock absorbers

Installation Notes and Fitment

Fits 2024-2025 Chevrolet Silverado 2500 HD, rear, w/o Lifted Package; Gas-a-just.

Fits 2025 Chevrolet Silverado 3500 HD, rear, Monotube Performance Upgrade; Gas-a-just.

Fits 2021-2024 Chevrolet Silverado 3500 HD, rear, Single Rear Wheels; Gas-a-just.

Fits 2024 GMC Sierra 2500 HD, rear, w/o Lifted Package; Gas-a-just.

Fits 2021-2024 GMC Sierra 3500 HD, rear, Single Rear Wheels; Gas-a-just.

Fits 2020-2023 Chevrolet Silverado 2500 HD, rear, w/o Off-Road Package; Gas-a-just.

Fits 2020-2023 GMC Sierra 2500 HD, rear, Monotube Performance Upgrade; Gas-a-just.

Fits 2011-2020 Chevrolet Silverado 3500 HD, rear, Install a monotube shock absorber to enhance performance.; Gas-a-just.

Fits 2015-2020 Chevrolet Silverado 3500 HD, rear, Monotube Performance Upgrade; Single Rear Wheels; Gas-a-just.

Fits 2011-2020 GMC Sierra 3500 HD, rear, Install a monotube shock absorber to enhance performance.; Gas-a-just.

Fits 2015-2020 GMC Sierra 3500 HD, rear, Monotube Performance Upgrade; Single Rear Wheels; Gas-a-just.

Fits 2011-2019 Chevrolet Silverado 2500 HD, rear, Install a monotube shock absorber to enhance performance.; Gas-a-just.

Fits 2011-2019 GMC Sierra 2500 HD, rear, Install a monotube shock absorber to enhance performance.; Gas-a-just.

Compressed length is 16.14 inches, extended length is 25.31 inches, and stroke length is 9.17 inches. Upper and lower mounts are E2 (14.6 x 42). Verify rear suspension configuration before ordering, especially on lifted trucks or models with package-specific notes.

Quality Assurance

KYB designs the Gas-a-Just line for performance-oriented truck suspension control, with monotube construction that separates gas and oil for consistent operation. Part number 554389 is built to meet the demands of GM heavy-duty rear suspension applications.