KYB 555603 Suspension Shock Absorber - Rear

KYB Gas-a-Just Rear Shock Absorber

KYB Gas-a-Just 555603 is a monotube rear shock absorber built as an OE-style replacement for vehicles that need restored control, consistent damping, and responsive handling. It is engineered for the Ford Crown Victoria and Mercury Marauder rear suspension applications listed below, including heavy-duty use cases such as taxi service.

Key Features

• Monotube OEM replacement design for direct suspension service
• Separate hydraulic and high-pressure nitrogen chambers for quick response and fade-resistant operation
• Triple chrome plated piston rod helps reduce seal wear from fluid leakage
• Higher gas pressure improves steering response and suspension control
• Built for vehicles that work, tow, or run larger, heavier tires and wheels
• Dust cover included
• Recommended with KYB strut mount SM5267 to reduce noise and vibration

Product Details

The KYB Gas-a-Just line is a monotube shock absorber series focused on restoring original suspension behavior with firmer response when demand increases. Part number 555603 uses a high-pressure monotube layout that keeps gas and oil separated, helping maintain consistent damping during normal driving and under load. For Ford Crown Victoria and Mercury Marauder rear applications, this design supports stable handling, improved steering response, and dependable control in everyday driving and heavier-duty service. This part cross-references Monroe Shocks & Struts (e.g., 550055) for the same application.

What It Helps Address

• Excessive rear-end bounce after bumps
• Reduced handling control from worn shock absorbers
• Fluid leakage related to seal wear
• Delayed response during steering and lane changes
• Fade in performance during demanding driving conditions

Installation Notes and Fitment

• Fits 2003-2011 Ford Crown Victoria, Rear; Recommended OEM Replacement; Mount kit SM5267 required with 555603; Gas-a-just
• Fits 2003-2011 Ford Crown Victoria, Rear; Recommended OEM Replacement; w/ Taxi Package; Mount kit SM5267 required with 555603; Gas-a-just
• Fits 2003-2004 Mercury Marauder, Rear; Recommended OEM Replacement; Mount kit SM5267 required with 555603; Gas-a-just

Verify rear suspension configuration before installation. KYB recommends new strut mounts, part number SM5267, to reduce noise and vibration. Confirm compressed length, extended length, and mount style match the vehicle before service. Part number 555603 is a rear shock absorber application for the Ford Crown Victoria and Mercury Marauder listed above.

Quality Assurance

KYB designs the Gas-a-Just line as an OE monotube replacement to restore factory-style suspension capability and control. The monotube construction, high-pressure gas charge, and chrome piston rod are used to support consistent operation and reduce wear in demanding rear suspension applications.