KYB KG5521 Shock Absorber - Rear

KYB Gas-a-Just Rear Shock for Classic and Full-Size Ford

The KYB Gas-a-just KG5521 is a rear suspension shock absorber built for drivers who want firmer control, quicker response, and stable damping under load. Its monotube design separates gas and oil for consistent performance, while the high-pressure nitrogen chamber helps maintain ride control during normal driving and when conditions demand more from the suspension.

Compatible With rear applications on 1968-1969 Chevrolet Camaro, 1968-1969 Pontiac Firebird, 1972-1979 Ford Thunderbird, 1972-1976 Mercury Montego, 1974-1979 Mercury Cougar, 1979-1986 Ford LTD, 1979-1982 Mercury Marquis, 1980-1983 Lincoln Mark VI, 1987-1991 Ford LTD Crown Victoria, 1987-1991 Mercury Colony Park, 1990-2002 Lincoln Town Car, 1992-2002 Ford Crown Victoria, and 1979-2002 Mercury Grand Marquis. The KYB Gas-a-just line is tuned for vehicles that work, tow, or run larger wheels and tires, and it is also a strong choice for classic muscle car suspension refreshes.

• Monotube shock absorber design for direct response and consistent damping
• Up to 25% more damping performance than original equipment shocks
• High-pressure gas and oil separation helps reduce fade from aeration
• Triple chrome plated piston rod helps reduce seal wear and fluid leakage
• Improved steering response from higher gas pressure
• Dust cover included
• Part number KG5521 for rear suspension applications

Why Drivers Choose Gas-a-Just

Gas-a-just shocks use two working chambers: an air-free hydraulic section for control and a high-pressure nitrogen section with a floating piston for added support. That design gives the rear suspension of a Ford Crown Victoria, Mercury Grand Marquis, or Lincoln Town Car a more controlled feel without sacrificing normal-road comfort. For classic applications such as the Camaro and Firebird rear suspension, KG5521 provides a monotube performance upgrade with valving suited to the vehicle platform.

Common Problems This Shock Can Address

• Excessive rear-end bounce after bumps or dips
• Reduced control when towing or carrying added weight
• Soft or inconsistent damping from worn OE shocks
• Fluid leakage caused by seal wear
• Delayed steering and chassis response from tired suspension components

Installation Notes and Fitment Tips

Fits 1992-2002 Ford Crown Victoria, rear; 1990-2002 Lincoln Town Car, rear; 1979-2002 Mercury Grand Marquis, rear; 1987-1991 Ford LTD Crown Victoria, rear; 1987-1991 Mercury Colony Park, rear; 1979-1986 Ford LTD, rear; 1980-1983 Lincoln Mark VI, rear; 1979-1982 Mercury Marquis, rear; 1977-1979 Ford Thunderbird, rear; 1972 Ford Thunderbird, rear; 1974-1979 Mercury Cougar, rear; 1972-1976 Mercury Montego, rear; 1968-1969 Chevrolet Camaro, rear; and 1968-1969 Pontiac Firebird, rear.

Verify compressed length, extended length, and stroke length against the vehicle’s suspension travel before installation. Lower mount type E1 and upper mount type S1 should match the original mounting style, and the included dust cover helps protect the rod surface during service. On Lincoln Town Car applications, follow the manufacturer’s instructions for the suspension strut and coil spring assembly.

Quality Assurance

KYB designs Gas-a-just shocks with a monotube layout and high-pressure gas separation to support fade-free operation and consistent damping. Part number KG5521 is built for rear suspension service across a wide range of Ford, Lincoln, Mercury, Chevrolet, and Pontiac applications, and it cross-references Monroe Shocks & Struts (e.g., 5961) for the same application.